Serenity

Is this the Shadows flickering problem? I was wondering if it got fixed
If it is here is a community solution, its a stock bug, scatterer used to fix it as well.
In the settings.cfg file find these settings and make sure they all = 1.
SHADOWS_FLIGHT_PROJECTION = 1
SHADOWS_KSC_PROJECTION = 1
SHADOWS_TRACKING_PROJECTION = 1
SHADOWS_EDITORS_PROJECTION = 1
SHADOWS_MAIN_PROJECTION = 1
SHADOWS_DEFAULT_PROJECTION = 1
 

I think this is right, replaced when Making History dropped:
The decoupler is replaced by the new TD-12 Decoupler. The TR-18A Stack Decoupler is a Decoupler that allows for staging rockets vertically and in sequence.
If you need to complete a contract then the Alt+F12->Contrats debug menu can help you complete it.

If you are on steam cut/paste the edited file somewhere else and then verify game files,
then you should have the original version and you can copy it somewhere else to have the reference.

If you go to Options and enable Advanced Tweakables you can use Autostruts.
Autostruts are far superior than the normal ones, they don't count as parts(less lag in big crafts), they don't appear visually so you avoid all these lines, they are just awesome.
You can right click almost any part and you can turn them on independently and your craft will be so sturdy, i recommend using grandparent only since heaviest is a bit tricky.
There are several posts-guides if you google, sometimes the normal ones are still used for visual reasons but autostruts is the way to go.

If you go to Options and enable Advanced Tweakables you can use Autostruts.
Autostruts are far superior than the normal ones, they don't count as parts(less lag in big crafts), they don't appear visually so you avoid all these lines, they are just awesome.
You can right click almost any part and you can turn them on independently and your craft will be so sturdy, i recommend using grandparent only since heaviest is a bit tricky.
There are several posts-guides if you google, sometimes the normal ones are still used for visual reasons but autostruts is the way to go.

Try this it might help, its from a similar problem but i strongly believe it will help in that annoying graphic bug as well.
https://forum.kerbalspaceprogram.com/index.php?/topic/195975-shadow-flickering-problem/
 

The Module Manager dll file must be in GameData.Which version you downloaded? 4.1.4 is the latest i think.
The other mods can be inside folders like Realplume but Module Manager needs to be outside, straight into GameData.
Like this:

The ingame Debug/Cheat menu has a landing cheat(Alt+F12 to open).
No need to use hyperedit anymore(it is/was a great mod though).
First quicksave though because it can be tricky to use.
You can find your coordinates/altitude from Flight Info i think in the debug menu.
It might involve some trial and error, maybe the simpliest thing to do is to cheat orbit the whole mission/skycrane to the orbit and do the landing again.
Sadly i could not find any tutorial how to properly use the landing cheat and been a while for me, haven't played the game in ages.

Yes, the ''bigger'' your save becomes the lower perfomance you will get.
I have restarted my save four times through the years and every time i got the same results.
Its not that bad though, its still playable with decent fps, the lengthy menu transitions are the most annoying part for me but what can you do...its fun to create big space programs.
 

https://bugs.kerbalspaceprogram.com/issues/25992
Known, game breaking bug, please upvote it, hopefully they fix it.
You can download Scatterer if you are ok using a mod to fix it.
I am sorry but this has been posted so many times,  its a bug that occurs everywhere, in every planet....in stock game without mods.

I think the easiest thing is to Alt+f12 Cheat Menu rendervouz with the station and just EvA transfer them if you dont want to dock.
or just Alt+F12 cheat orbit the whole station with the kerbals inside....if you dont/cant EvA yet.
There are lots of youtube videos on this, most of them are long but worth to learn how.
Do you know Mechjeb?
It has Rendervouz autopilot and some sort of auto docking, it might help you at least to get close to the station
and give you some guides of how to approach and how to dock etc.
 
 

Those two mods shouldnt have much impact on your save to corrupt it, hopefully a new install will fix it, just backup your saves folder,
inside saves folder there is also a ''Backup'' which contains previous persistent files, you might try one of them to see if it works.
worst case scenario i guess you can transfer your crafts to a new save, backup often its helpful :p.
Uhh i am guessing your not on steam to just verify files?

If you have the option enabled for kerbals to respawn, they take a while to come back after they ''vanished''.
To bring him sooner i think you can do something from Alt F12 to bring him back faster,
and if you google a bit you can go to persistent file and change his status
I found this, i am 99% sure it works but...you know back up first.
Try this:
1.Open your persistent.sfs file with Notepad.
2. Find this section:
KERBAL { name = Jebediah Kerman gender = Male type = Crew trait = Pilot brave = 0.5 dumb = 0.5 badS = True veteran = True tour = False state = Missing inactive = False inactiveTimeEnd = 0 gExperienced = 0 outDueToG = False ToD = 804399.44100609387 idx = 0 extraXP = 0 CAREER_LOG { flight = XX XX = Die } FLIGHT_LOG { flight = 11 11 = Land,Kerbin } } 3. Switch the state to "Available"
4. Remove any line with "Die" under CAREER_LOG and FLIGHT_LOG
Jebediah should be back, ready to die again.

Are you on Steam?If you are try to Verify the files, Right Click Kerbal in Library->Properties->Local Files->Verify Intergrity
Also from the Properties->Updates Disable Cloud Saving.
Last if you open Local Files it opens the game directory, there you find the ''saves'' folder, always backup that, and the ''Gamedata'' is the place you put mods.

Make sure you disable steam cloud from Library and not from general settings(Just in case), Right Click on Kerbal->Properties->Updates->Steam Cloud
Have you tried of clearing the download cache?Steam->Settings->Downloads.

Yeah, messing around with fuel priorities and sometimes with decouples messes up the DV calculations  .I use a mod to see the true DV but i sure hope so it will get fixed soon.There are 2-3 posts in the last month that mention the same problem so i am  guessing its not limited to few users.

You probably have Steam Cloud Saving enabled.
Go to Library->Right Click Kerbal->Properties->Updates see if Steam cloud is on.
If its not that, maybe try to do a clean install since sometimes the Verify integrity Files gets bugged out.

Alt+F12 is the Debug/Cheat Menu of the Game(You can do many many things from there).
https://imgur.com/qOER8MF Press the Facilities button.
Rightshift+F12 For linux maybe.Not sure, google it a bit more  .

Both of these mods work/updated fine in 1.4.3

Are you on steam?Verifying doesnt endanger your save files, its just a checkup not an install.
If yes, go to Steam Library, right click on Kerbal --->Properties-->Local Files-->Verify Integrity of Game Files
You can also click there the Browse Local Files--->
Gamedata folder has your mods 
and saves folder has your saves.
You can backup those two folders and do a clean install without fear(if the verify doesn't fix it).

Can you give some more info that might help?
Are you on 64 bit or 32?And are you launching the correct one?
Steam?Did you do a clean install or verify files?(if you are on steam)
Are you starting the game as administrator?Did you start a new save or an old one?
I hope you find the solution, maybe someone with more expertise can pinpoint the problem.