A_name

Make sure you have advanced tweakables on in the main settings menu.

I've never tried such an aggressive aerocapture myself but 8 Km/s does seem to be way too fast, and a periapsis of 13 Km seems too steep as well. What I can tell you is that there is indeed a certain speed where no heat shield will save you, even in Duna’s thin atmosphere. So there’s basically only two ways to solve your problem, slowing down before entering the atmosphere and/or going for a higher periapsis. Your solution will likely be a combination of both. You’ll probably need to do lots of trial and error in your “simulations” to find the maximum speed and minimum Pe where you won’t explode but will still capture. Just from memory, using a typical Hohmann transfer you would enter the atmo at about 5 Km/s so try shooting for a speed around that range and a slightly higher Pe of maybe 20-30 Km.


 
As to the Scott Manley video you mentioned, atmosphere and part physics are all tweaked for RSS so it’s normal that you could pull it off there on not in stock.

These are all good answers but none address the underlying issue. Even with SAS turned off, there should be no reason why the craft should start rotating unless there's an external force applied. The mere act of going EVA and letting go of the ladder does not exert torque over a ship.
 
My guess is that OP is using the Mk-1 capsule with a part attached to the top that is slightly clipping through the hatch. This situation WILL induce a force on the capsule when a Kerbal goes EVA (the Kerbal also is sometimes flung away at high speed in these instances). Usual culprits are batteries, probe cores and other components placed on top of the capsule (the small parachute is safe to use, never had a problem with that part in particular). Use the offset tool with fine control (press 'c') to move the part ever so slightly so that it's not fitting so tight against the capsule. This usually fixes the issue.

Have a look at my gravity turn tutorial. I haven't properly updated the thread for 1.2 but the methods described still work:
 
 

Use the Trajectories mod, it will show you a red 'X' marker where you are predicted to land. If you want to keep it stock, trial and error is the only real way. This is because your landing spot will be influenced by a bunch of factors including the shape and size of your orbit and that of your craft. For a LKO, I usually burn over the deserts west of the KSC continent and aim for my orbit to touch the ground east of KSC on the peninsula that looks like Korea.
Additionally, if you're using a spaceplane, you have the advantage that you can significantly alter your landing spot by maneuvering in the air during descent. So keep switching to map view to see how your trajectory is behaving and adjust accordingly. As others mention, increasing your AoA (that is, pitching up or down, or sideways while banking) creates drag and slows you down. If you're overshooting, increase your AoA and if you're undershooting point more prograde to reduce drag. In the upper atmosphere it's all about drag. But as you hit the light blue part of the atmosphere meter, you'll start generating lift, so flexibility increases. Here you can make significant trajectory changes by maneuvering like a plane as needed.
 
Or you can land on the island runway!

Well, the most important part is to have your COL behind your COM. Not too far behind, otherwise it'll be uncontrollable, just touching it. Then you need to make sure it stays that way. Drain the fuel from your tanks and see how your COM moves. If it ever moves behind the COL you need to adjust so that it doesn't.
Now to your specific issues:
"incredibly hard to control "
Assuming you already balanced your COL and COM as described above, you need more control surfaces. Also, make sure you use the right click menu on each control surface so that they only control the direction of movement they're supposed to. This means, for example, for your rudder deactivate pith and roll and only leave yaw, or for elevators deactivate roll and yaw and leave pitch.
"pretty much impossible to land"
This can also be due to not enough control surfaces, or due to not enough lift. Add more control surfaces and/or more wing parts.
"my planes explode on the runway"
Use struts.
"they take off then crash into the ground after flying for 5 meters"
Not enough control surfaces or incorrect COL - COM balance.
Planes in KSP aren't supposed to be hard. Keep it simple at first and work your way up. Learn to walk before running.
Happy to answer follow up questions.

Even with a more conservative periapsis, even with suborbital flights, slowing down in time to open your chutes can still be tricky. This is only part of the solution.
I agree, the other part of the solution is aerodynamics. The "fin trick" is one option that works well, but the underlying principle is to use drag to help you slow down and this can be done in several ways. Sometimes it's enough to use your SAS to force your craft to travel through the atmosphere at an angle, exposing more surface to the air.