Cycling the tank is really like you'd cycle any other tank.Safer if fishless cycling of course.

As for salinity,I know that different fish like different amounts,so you'd have to google the fish that you're interested in to learn a bit more. In general,it seems like most I've read about use the 0.2 % range,but you're better off looking up those specific fish.If you google "Starting,or how to start a Brackish Tank",you should be able to find a lot of "how to" articles