Twitter Limits

I have heard people say following 500 people a day on Twitter is OK. I have also heard that you can use 5 accounts per IP. Does that mean with 5 proxies I can potentially follow about 10,000 people a day if I don't do it linearly?

also, when logging into an account will it get banned if I log into it via difficult. IP's within the same country?

Thanks

And what about logging in to the account via different ip?