How to get banned from Twitter? I guess if you use it normally you don't even need to worry on this issue.
Asking for a maximium sounds like you want to spam via Twitter and sooner or later you will be banned if so
I've been successful adding 70 monday, tuesday then removing 50 thursday friday and sat. That's just my routine though, i'm sure you can get away with more. I use tweetwhistle.
How many are you thinking about doing a day? I'd imagine if it isn't an insane amount, and doesn't just look like spam, you should be fine
If you cross the limit between the Followers and following you, it stops you to follow more people till you have a good ratio
you can safely follow 1,000 people a day you can not follow more then 10% more than are following you. Might check out this article on Social Media and building your followers.