bewing

Fly as high as you can, as fast as you can, without burning up. The rapiers will probably take you to 1500 m/s, but your plane may overheat on Laythe at that speed. But yes, you can fairly easily fly from Kerbin's equator to the poles and back on 400 fuel. So you should be able to do it on Laythe too.

As far as I'm concerned, this is exactly why god put other planets in the solar system. They exist to do your plane change maneuvers for you. You may not think slingshots give you enough of a dV boost to do you much good, but they can pretty much eliminate the need for plane changes, and those are very dV-expensive things.

The target orbit has nodes on it. Those nodes are relative to the vessel that currently has focus. If those nodes say 180 degrees when you hover your cursor over them, then you are orbiting the wrong way around. The nodes on your target orbit need to say zero (or actually, 2 is always good enough, but getting it to zero helps with matching the other orbit parameters).

Transmitting science takes a hell of a lot of EC. So yes, you can set it to do partial transmissions, but you will need to babysit the transmission realtime for hours and hours if you do.

Yes, that is correct. One thing you may need to take into account is a bug that may still exist. At level 3, the Admin building sometimes doubles your commitment from what you try to set. So if you try 100%, it may tell you that's impossible (because that's really 200%). If you try 50%, it may double it to 100%, which is what you want. (Please try it, and let me know if the bug still exists.) Converting funds to rep is extremely inefficient. I'd say, set the commitment way down at something like 10%. Then, whenever you want to get rid of some funds, do a one-time conversion instead. And you can be certain you will always have enough funds to launch.

At what level of gravity, and atmosphere or no atmosphere? Those are the two biggest design issues.

Engines are heavy, and you have too many. Also, you have no incidence on your wings. You have too many air intakes. You have no canards to provide efficient control. Struts have drag and mass -- you should use autostruts instead. Your nacelles should be mounted to your fuselage and not your wings.

Sandbox is all about practicing maneuvers and having fun. How would you like to practice flying Kerbals around the universe? You can turn on infinite fuel and "ignore heat", and then fly your Kerbals all the way home with their jetpacks and parachutes!

I think there was one version of KSP where you could transfer EVA propellant between Kerbals if they were close enough to each other. Otherwise, the only way to refill the EVA propellant is to board a command pod and then EVA again.

Either you can hit F3 just after the wings explode, and the report will tell you what happened to them, or you can turn on the extended temperature debug readouts in the debug menu. Then open the context menus for the wings while you are in flight and watch the numbers change in realtime.

The very best way of making money from contracts is to figure out clever ways to complete multiple contracts with a single flight. The more contracts you can complete with one launch, the more money you make.

Theoretically, yes -- but that can easily unbalance your plane and overcome the ability of your control surfaces to compensate. It's a lot easier just to pump a little fuel around when you need to.

Pump all your fuel as far forward as you can, before you reenter, to get your CoM as far forward as you can.

Put them on the nacelles of your carrier, approximately inline with your spaceplane's canards. Your stabilizers shouldn't be adding any lift, so removing them shouldn't change your CoL. Air is shared all over the surface of your craft. So you don't need a path from the intake to the engine, unless you are trying for realism. Part of the point is that I don't think you need that many rapiers, either. Each of your engines is mounted on a short nacelle -- so you make the nacelle longer, stick a 1.25 bicoupler at the back end, and attach 2 rapiers. Or, you use the fact that rapiers are stackable and you stack maybe three of them and use the move tool just enough to make sure their exhaust plumes don't get mutually obstructed. (Unless you are a fanatic about clipping.) Additionally, since you aren't using all/any of those rapiers for the "rocket phase" of your ascent -- whiplashes give you more oomph for a lot less mass. You gotta either use the non-airbreathing function of the rapiers, or you should ditch them for better engines (whiplashes). It's almost never a good idea to mount engines directly on wings. It would almost certainly be better to attach your rapier nacelles directly to the sides of your main NERV nacelles. But the FAT455 wings have no heat resistance, and will almost always burn off of any spaceplane unless you treat them like they are made out of feathers or something else that's flammable. Part of the point of spaceplanes is the flight path that you take. You have a lot of drag and a lot of wing. That's kind of a bad combination. With a lot of wing, generally you want a shallow ascent that stays in the atmosphere for at least 10 minutes. Climbing at no more than 5 degrees, with an additional 5 degree AoA at most. And since you're in the atmosphere a long time, you need to be super careful about minimizing drag and part count. If you're just going to point the nose at the sky and light the rockets -- then NERVs are a bad choice. It takes them a very long time to get a spaceplane to 70km and orbital velocity. The maximum realistic mass for a spaceplane powered by 2 NERVs is about 50 tonnes, and yours is definitely too heavy -- and you again need a shallow ascent with NERVs to give them time to develop all that deltaV. If you want a steep ascent, then you need to use Ox powered rockets (like the rapiers), and you can probably get away with a lot less wing. You put the Lf+Ox tanks on your nacelles, and make them longer.

Well, lots of little issues. First, to prevent runway veering/sliding -- you want lots of friction on your rear wheels only. Remove the friction on your front wheels. Drag at the front end causes instability which causes veering. Drag at the back end is helpful. Rear stabilizers cause a lot more drag than canards, and they do not provide lift like canards do. Delete those stabilizers and use tailfins for canards on the carrier. Each air intake adds drag, and you only need about 1 intake for every 4 engines. So you've got way too many air intakes. Each elevon on the wing adds drag and mass. Maybe the ones way out at the tips are useful (because they provide the most torque), but get rid of all the others. You want to minimize the mass (and therefore part count) of the stuff you are dragging into orbit. Can you replace a chunk of those wings with a single BigS wing? BigS wings hold fuel, so they can help you eliminate fuel tanks. (Sorry, but I didn't download and examine your craft file.) Do you have a probe core somewhere on that carrier? It can't fly without one. You have a lot of reaction wheels and they eat a lot of power. Are you sure you have enough batteries?