If your thinking of 4mm Eva Line grab some duo fittings to go with it, 4mm a pain to get on otherwise. A fan will certainly help with moisture and spreads the temp more even through the keeper. With line length either start with say 2 metres and just shorten if necessary, you can download a line calculator but don't know if it works with flow control taps.
I agree with the others posting here. Steer clear of flow control taps. I would go with the flow control disconnects from Kegland along with their 5mm beer line (it's way better quality than the Keg King line that I used when I first set up my kegerator and had all sorts of problems with) and Duotight fittings. They really make setting up your keezer/kegerator a breeze and I've had zero issues with gas or beer leaking.
A bit late now!! [emoji23]
They've been pretty good so far I reckon. A bit foamy but I also put that down to warmer beer in the lines in the tower. Dunno though. The flow control does allow to pour slower if need be which helps a bit too I think.
I'll persist with them for a bit as I don't want to fork out much more $$$ on it.