1). Don't. If you have to leave the helmet with the bike, chain it to the seat through the chinbar, and loop the chain under the sub frame.
2). M&P, Busters, Independants, occassionally Halfords have deals on their semi synth oil and coolants), and, sometimes, even bike shops have the best deals
3). See 2). and FWR in S London do good deals on C&S kits.
Just make sure that the soft link is WELL flttened.
4).As long as you lube the chain, any make will do. For me, the biggesty thing is how long does it take to remove from the rear wheel. Hence I have a Scotoiler. Have used them for 6 or 7 years without problems.
Welcome aboard. Gosh, my throat is dry this evening.

Fek-Yet
another project for the back of the garage.