Free vpns/proxies are a bad idea there are thousands of botters across multiple botting sites and surely many of them have used those ip
1: Idk if any of those really makes any difference i couldnt say but keep doing those and see wat the results are, sounds like you are botting f2p if thats the case i wouldnt bother trying to save the accounts just suicide them
2: Yes u can use ur osbot account over separate ips. But why are you using a VM to bot on?
3: I dont understand what u are asking, are you asking if one of the bots get banned will it affect the mule?
4: If you find a good method that makes good money then yes its worth it to invest in a private script. If the free script you are using shows good performances/low banrate u could keep using them
5: You shouldnt expect anyone to tell you their method this you will have to find out on your own just trial and error