HvP

As a kid I amazed my friends by constructing simple ring shaped paper airplanes and flying them right in front of their eyes. If you don't believe it then just do a google search for round paper airplanes. Have fun.

Realism for what... Earth? It's not Earth it's Kerbin, a different planet altogether in a different system. Why should we expect a rocket that performs well on Earth to perform well on Kerbin, or vice versa? Why should we expect a similar launch profile, air density, or jet engine performance? Earth and Venus are about as similar as any two planets in our real solar system and yet I highly doubt you could expect any rocket designed for flight on Earth to work properly in the atmosphere of Venus. Why should it do so on Kerbin? You have to learn to design within the parameters of the system you are designing for.

You didn't mention if you were trying to connect them to different parts on the same ship or to two different ships. The KAS struts can only be attached to parts that the game identifies as the same ship. This includes ships connected via docking ports or if you have connected the KAS fuel transfer pipes first. You will not be able to connect struts between two completely disconnected ships at all.

Both approaches certainly have their advantages, but if you're going to send multiple launches within the same window then I would highly recommend the Kerbal Alarm Clock mod. It will give you a heads up when any planned maneuver is upcoming and can even stop time acceleration when any ship is approaching a burn or SOI change whether they are focused or not. It greatly relieves the stress of checking in on which ship needs attention next. Personally, I prefer to run with at most a mothership for orbit that launches a probe or lander and maybe a fuel supply ship following up.

Was very proud of the orbital station I made and was looking forward to using a robotic arm I built using Kerbal Attachment System and Infernal Robotics. But the arm needed to be sent up in a separate launch and attached via a docking port sr. I had it all worked out. (a) The arm would be brought up attached to a tug. ( The electromagnet on the end of the arm would grab the station. © As I had a probe core on the arm assembly I would be able to maneuver the arm's docking base onto the station using the robot arm in reverse. It was going well. Successful rendezvous, perfect alignment of the arm, even the rotational axis was spot on. Electromagnet engaged and holding. Bend the arm so that the tug is aiming at a right angle to eject away from the base and prepare to bend the arm 90 degrees to drop the now open docking port down into contact with the one on top of my station. Decouple and... immediately lose power because my batteries were on the tug. I was able to ponder the relationship between electromagnets and electricity as my robotic arm floated serenely off into the sunset.

There are only a couple of things I can think of that haven't been mentioned. Is control given to a part oriented in the correct direction? If a probe core or docking port that is oriented upwards has control then it might not know where "backwards" is from the perspective of the command chair. Make sure that you "control from" the command chair. If it's happening on other crafts then this is unlikely but worth checking. Also, make sure that the new key binding you set up doesn't have the same key for "backwards throttle" assigned to some other function already. I've found that having the same key mapped for two different functions that could overlap can really confuse things, especially now that each key binding can have a secondary function. Also, make sure that you have the button checked to be enabled in the scene for "Staging/docking" modes depending on how you drive. Lastly, I don't know if you have any mods installed like Action Groups Extended, but it can set action groups to "Toggle" rather than a simple press and hold. If you are using Windows I'd also just check and make sure that "sticky keys" isn't turned on in accessibility.