Questions about cryptocurrency mining.

Hello to everyone I'm new to mining and I have some questions for someone involved in the cryptocurrency mining business. First of all what is the cost to set up a mining rig? What currency is it profitable to mine? How to setup a mining rig? What kind of hardware and software is needed? I saw a post here that someone mined ethereum and with an initial investment of 2500 $ he made 15,93 daily. That's about 5k annually. Is such roi achievable? What is the roi of a mining rig in general? And is it better to mine proof of stake cryptocurrencies like peercoin or normal proof of work cryptocurrencies.