New XT600E owner with some questions

[TakisMp]

Hello guys,new to the whole site/forum,but have read many threads the past couple of months.I've made an account because i'm about to be a proud yamaha xt 600 e 1997 owner and I have some questions.

So with all the preparation and the anticipation comes also a big fuss about parts and choices for the bike.

First of all,it's going to be a super moto,that's decided.So here are my questions:

1)Is there an oil that's objectively good on the bike? I've heard 15-50 is the best choice,but belray? motul?
2)What dimensions of supermoto wheels are the best? I've read 3.50x17 and 4.25x17 are the best cause of the whole lack of power of the xt and that a 5 rear would be too much.
3)I want to put an oversized 320mm disc brake in the front.Any good suggestions?
4)I've also read a 44 tooth rear makes a lot of difference on how the bike works,gives a little less acceleration but better top end for cruising.Is that correct or it's a waste of time?
5)What about tyres? I do 99.9% street riding and I want good grip on the wet.

Thanks a lot,cheers from Greece.