Reactordrone

In my experience the contracts for Duna and Eve come up as you are approaching the first transfer windows. If you've been playing around the Mun and Minmus for a long time you might have missed the Duna window so it brings up the Eve contract first.

For Mk3 planes there are a couple of fuel tanks you can use at the back, the Mk3 to Mk2 adapter and the Mk3 to 2.5m adapter.

You can effectively ignore the Mun to determine where you need to burn to reduce the altitude of the other side of your orbit. If the Mun wasn't there you would burn retrograde to lower the other side of your orbit so with the Mun in the picture you want the escape from the Mun to be tangential to the Mun's orbit and retrograde, i.e about 90° further around than you're doing it. https://imgur.com/W8XnKRb

You're burning on the wrong side of the Mun but the new orbit is the one in Kerbin's sphere of influence rather than the Mun and you do want to see where the orbit will be relative to Kerbin.

Get into the same orbital plane as the target spacecraft and have your orbit touch the target spacecraft's orbit at one point. If you're behind the other vehicle you want the rest of you orbit to be lower so that you orbit slightly faster and close the range with successive orbits. If you're ahead of the other vehicle you want your orbit to be higher so that you orbit slower than the other ship and they catch up a little bit with each orbit. If you have your tracking station and mission control upgraded you'll be able to select the other ship and see where the two ships will be in the next orbit. If you're not upgraded you can select a target by clicking on it when it gets within 100km. You can then switch the navball to target mode when you're getting close and try to line up your prograde marker to the target prograde marker (and retrograde to target retrograde).

If you have any other part right clicked you won't be able to transfer fuel so make sure you don't have any science instruments , engine or command pods open.

Minmus to Kerbin to Eve (165m/s to Kerbin + 110m/s boost close to Kerbin) can shave off a couple of hundred m/s compared to a Minmus to Eve transfer. It does make timing more difficult though.

You can also try going up hills in a zig zag. It reduces the effective incline by increasing the distance travelled for the altitude gain.

Going up it's flyable, you just have to be gentle with your initial turn since it has very little control authority. Coming down it will want to flip head first so you might want to put an extra decoupler on to get rid of that service bay.

Note that you can't send tourists outside your ship so if you need to transfer tourists and VIPs between ships(to a lander for example) they will need to be docked together to allow internal transfer.

On an external command seat I'm assuming.

At that point in the training you just need to execute the planned burn to bring up the next window. You may want to adjust your node a little to get the periapsis at the Mun above the surface.

First fifth landing successful. Finally saw the tension arms releasing during deployment.

It's very much going to depend on the mass of you vehicle. If you're making an 18t ship another 1.5t of engine is going to reduce the delta v. The first stage has to be designed to account for the second stage and third stage mass and you're going to end up with a larger vehicle to have the same delta v or more delta v.

Duna is pretty safe to aerobrake at if you have a normal Hohmann transfer. The relatively low speeds and thin atmosphere means less thermal problems so most things can aerocapture without any heat shielding. Retract solar arrays and antennas and aim for 15-20km above the surface.