1. I'd say 2-3 times a week is all that's necessary, and you only need to test ammonia and nitrite at first. Once ammonia goes to 0ppm and nitrites are high, start testing nitrate. Once ammonia and nitrites are consistently at 0ppm, and nitrates are high, the cycle should be complete.
2. At least once a week, probably more when you initially add the livestock. But say, after 3 months, the tank should be stable and mature enough that you should only need weekly testing of things like ammonia/nitrite/nitrate.
Now, if you've got a reef setup (corals, etc) you'll need to test calcium and alkalinity levels, and those you might have to do 2-3 times a week, until you learn how rapidly the tank uses calcium and alk
, so that you can add those back with a 2-part system.