"How often should I test water?" - If your cycle is completed, there's no need to test if there are no changes in the system. I would test after water changes and 1 and 3 days after adding new inhabitants. For corals you definitely need thorough testing before getting them. (Alk, Ca and Mg)
"What are some good choices for coral?" -It depends on your lighting, flow, maintenance patterns and water parameters. So, needless to say, it's hard to say without all that.
"How do I feed coral?" -Same thing here. Different coral have different dietary needs and responses. From 'no food needed' to 'spot feeding required'.
"Should I put some fish in?" -I believe you certainly can if the cycle is done. Only one at a time, 3 weeks apart. Start with the least aggressive/territorial and move up. Have a plan before buying as it's a common mistake to fall on the impulse buying pattern of visiting the LFS and buying what's pretty.
