You may struggle to get to the bath waste. However, might be ok if you remove the section where the branch and basin are. Could always get a basin connection on a wc boss.
If it’s being used as a 1 way then L1 isn’t used as per mi’s. Also, have a look here: http://www.varilight.co.uk/technical-section/faqs-troubleshooting.php
If it’s the same manufacturer, the brackets may line up. As for the trv replacement, you may need to partially drain the system, all depends on which type you have.
Don't know really. I don’t have a lot of free time to study, I easily lose concentration and would be better suited in a classroom environment. I get these pipe dreams now and again (not just because I’m a gas engineer :laugh:).
A bit of toing and froing on this but for the time being have decided against learning electrics as I don’t feel I have the right mind set currently to do it. I might go back to learning woodwork, but who knows. Vicious cycle atm.