Favad this is not a question these are many questions
Over the past there have been two version of RIMS have been seen 1.85' (2008 & 2009 model) and 2.15 from 2008 uptill now.
front is 1.85 from start till now as i know.
120/70-18 maximum but thats not a good Idea (Power is reduced) 110/70-18 will be a good shot.
yes curent chain is enough
12~20k depending merely on Luck and hard mechanics follow ups.
I hope it may help.