What do the numbers followed by the letter c given to individual parts that you haven't researched yet mean? Can you research individual parts? Note: If you install a mod like mechjeb and you've already researched flight control you can click on the mechjeb 2 case and it will ask you if you want to research that part.
Wrong, parking low saves feul coming into a system at 4 km/s and having to decelerate down to 2 km/s is less feul used than having to decelerate down to 500 m/s vice versa on exit
Thing is that you won't be able to keep spamming the same thing in later versions, it'll work now but still, it's going to take longer and for later techs where you'll need longer missions it isn't really time economic.