If your account is banned , and I bought a new account and play it with the same ip , whether it increases the risk of banning new account?
this is very true and correct. if you get banned, make sure to re-format/factory restore with windows 10 though since blizzard tracks wow install/reg keys i learnt this the hard way, even after re-installing wow i was getting screwed straight away and flagged until i stopped being lazy and listened to some of the big boys and wiped my system clean and after that no more issues. do this after any ban.
I had many accounts running at the same time during MoP and only in rare occasions they all got banned at once on my static IP.
I have been playing with different configurations and it seems to be a bit safer (at least with my limited testing) to only run one or two bots per machine. I'm not sure why, but if I run 4 or more bots on the same box, I get manually banned quickly.