I don't think so. I have more than 5 investors in my PAMM account and I got no warnings from my broker about volume of investors I have. Ask your broker directly to confirm.

It is not bad to have a lot of investors because it is the advantage for both of you - you and your broker. PAMM account is specially designed to attract and get more investors.

No, there's no limit. HIgher volume of investors make you more profitable and of course, your broker would not prevents you getting a lot of clients. It's very clear that they would gain a lot of money from you and from your investors.