Take a look at whattomine and some of the information available and you will find the answers to your questions. Depends on the price of your electricity which you will need to look up to find out what you can estimate your profits to be.
Use mycryptobuddy, do NOT use cryptocompare. It's 100% misleading and will cause you to lose a bunch of money.
how can i know how much H/s RX560 or RX580 have?
electricity is about $0.14 per 1KWH
If electricity is $.14 per kWh, you're not going to make any money unless price goes up drastically, at which you might as well just have bought coins. Your electricity is too high and you're too late, it would be a bad investment to start now.