Anyone using Instagram

The safe number of people to add before instagram bans your account is not specified. You should follow the bellow steps to safe your accounts-
# If someone is sharing photos or videos that make you uncomfortable, you can unfollow or block them. You can also report something that you feel violates our Community Guidelines right from the app.
# Make sure you know whether your account is public or private. When you set your posts to private, anyone who wants to see your posts, followers or following list will have to send you a follow request first.
# If someone is bullying you, reach out to a trusted family member or teacher for help. You can also remove a comment from a photo you've shared and report bullying and harassment through the Help Center.
# Make sure you're comfortable letting the photos and videos you share represent who you are to a wide audience, such as your parents, teachers or employers.
# Never agree to do something or share anything that makes you uncomfortable.

The limited number of people you can follow on Instagram is 7500. And from what I know, Instagram only allows you to follow or unfollow about 150 people per hour. Anyway, take it easy. If you follow too many people within an hour, you will only receive a message telling you the limit has been reached.

Still, I'd suggest you to be careful with URLs you post, repetitive comments and hash tags.

Yes, there is some limits for connecting with peoples or following them.
According to the rules of Instagram, the number of people you can follow is 7500 in order to reduce spam.