1 - Water parameters - Shoot for 0 ammonia / nitrites and as close to 0 nitrates and phosphates as you can get. pH around 8.1. The other parameters don't really matter as long as you don't have coral
2 - Salt - Just mix the salt with the water. RO
water is better, but RO
will work. Instant Ocean is a pretty standard salt brand to use. It should have everything you need.
3 - Food - Food from the store would be best. Particularly something like clams that it can bash into pieces but shrimp will work as well.
4 - Live rock is the filtration for your tank. Approximately 1 lb + of rock per gallon of water is sufficient.
5 - Flow - Shoot for 10x-40x the tank volume per hour in flow. It doesn't matter what you use, but most people use powerheads. The hydor koralia are probably the most popular value brand. However, your aquaclear filters will work just fine. Be careful tho, I've seen videos where a mantis shrimp decided it didn't like a filter in the tank and decided it would look better in more pieces. On that note, a metal heater would be a good choice.