Geonovast

F4 toggles the brackets.

Fuel cells only produce EC when the batteries get below a certain threshold.  I want to say it's 85%.  If your batteries are below that, then some screenshots would help.

You don't need a high GPU, but I really recommend that you have a discrete GPU just to take that load off your CPU and free up some of your RAM.
Keep in mind though that this game can still bring even high-end chips to their knees with enough mods and big enough ships.

The way the sale is set up right now, you would only save $2.53 buying the DLCs separate from getting the whole bundle.
Personally I would just buy the bundle.
But AFAIK, you can actually buy the DLCs from Steam and then just put the folders into your store install... at least I've seen that mentioned recently on the forum.

You wait for 1.7.3
 

If you don't care about the other launch sites at all, like me, you might want to take a look at Making Less History.
 

It's actually quite simple.
Just make a new text file with the patch in it.
This part:
@PART[Akita_Seat] { CrewCapacity = 1 }  
It doesn't matter what the file is called, as long as it ends with .cfg
Put the file literally anywhere inside your GameData folder.  I recommend making a folder called MyPatches or something similar, so you can keep track of all your personal patches.
Make sure you have ModuleManager installed, and you're good to go!

As far as I know, it should work.
Personally I would just back up the save, and give it the ole' college try.

The game doesn't care which way the air brakes face.  It's up to you.  However you think it looks better.
Your picture is misleading because it doesn't indicate which way you're going... although as I said, it doesn't matter. 
Here's an image of a real one if it helps.

In stock, you can't really.  Anything outside the physics bubble (which is around the ship you're in focus on) will be auto-deleted if it's on a suborbital trajectory when it gets below a certain altitude.  Sometimes you can get away with it if your payload is going to a really high orbit, where you have time to switch to the booster and get it landed, then switch back to your upper stage and get your payload to orbit before it crashes down.
If you just care about recovering for funds, you'll want:
If you want to land it manually after you get your payload to orbit, you'll want:
 

Neither of those antennas is a relay antenna.
Direct antennas cannot talk to each other, they can only talk to relay antennas or the dishes at the KSC.
The antenna actually has to say relay on the description in the VAB.
This lists all the stock antennas and if they're a relay or not.
https://wiki.kerbalspaceprogram.com/wiki/Parts#Communication

I hope not.
I'll refer you to the dozens of threads where multiplayer is thoroughly discussed and no agreement is ever found to take care of the handful of multiplayer game-breaking issues.

@Silviu250, take a look at this:
 

Haven't tried this in awhile, but it might still be relevant.
 

Here's the mod.  Should still work for 1.5.1.  You'll need module manager.
https://spacedock.info/mod/137/Discontinued Parts
From this thread:
 

Changing your inclination also affects your pe and/or ap.  When you're setting the manuever node, you need to also adjust the prograde and retrograde handles to keep your orbit where you want.  So move the normal  or antinormal  handles until your projected orbit gets significantly larger, then pull the prograde  or retrograde  handle to shrink it back down.  You'll have to go back and fourth a few times to get your orbit exactly where you want, then do your burn.

Either you lost signal or you ran out of electricity.  Do you have a screenshot?

Do you have the rotation snap enabled?  Bottom right, it's the button that cycles between a yellow circle and a yellow hexagon.  Circle = off, Hexagon = on.
Unless you're talking about something else, in which case we could use some screenshots.
Welcome aboard, @aaronpachta!

Are you warping while still in the atmosphere?  If you are, it's using physics warp, which can cause ships to become unstable, depending on their design.  It even warns you about using it when you use it.
If it's standard warp in space, can you record a video of it happening?  Also, are you using any mods?

Sounds like it's a borked install.  Steam has a "Verify File Integrity" option or something, doesn't it?  I would try that first.

Normally I would blame version incompatibility, but I would think... I would HOPE that Steam would handle that correctly.

From the looks of it, you're early in career, and you haven't unlocked the node in the tech tree that allows crossfeed.  I believe it's the one that has the fuel line it in.
 
Edit: Oh!  First post!  Welcome to the forum @TanoPrime!

If you right click on any fuel tanks, there will be a button that says something like "Show fuel flow overlay"
You might need advanced tweakables on... but I don't think so.

Sorry @HyperDraco, I think you either just have too many parts, or, way, way too much clipping.  I didn't get too into it because it was pretty choppy in the SPH, but I did see a lot of graphical shimmering.  It did launch, though, and survive for a few seconds.
Had about 4 seconds per frame during the explosion.  What you see is what I saw.  Keep in mind this is a 4.2 Ghz i7-7700K with 32 GB of RAM running at 3333 mhz and a 6GB GTX-1060.
The yellow messages from PhysicsRangeExtender aren't showing up on the screenshots, but the explosion seems to coincide with that finishing doing whatever it's doing.
I think you should start over, and keep part count in mind.
I was going to turn on unbreakable joints... but it was already on.  Is that something BDA does automatically?

Advanced Tweakables needs to be on for that.  I believe it's under your difficulty settings?  Might be the regular game settings.

So you installed 1.5 directly over your old installation?

That could have left artefacts that's causing an issue.  Install everything again, but to a different location, and see if that one launches.