So if I post an address on a website and multiple people sent bitcoin to it I'll be OK? I'll get all the coin?
100 addresses? That's insane. That's like going to the bank and them giving you 100 checking account numbers. WTF? I thought it was safe to post and use an address?
Yes, it's fine to use a single address if that's easier. The reason people use multiple addresses, however, is because all Bitcoin transactions are entirely public and recorded and so using a different address for each transaction is a good way to retain privacy.