Some of your questions can't really be fully answered until you know which insulin you're going to be using. Lantus, Levemir and ProZinc are the 3 types of insulin that are best for cats.
Generally, we Test/Feed/Shoot in the morning....Test to make sure they're high enough for insulin, Feed to make sure they're eating, and shoot....all within about 5-10 minutes....BUT, if you're using a harsher insulin like Vetsulin/Caninsulin, you want to Test/Feed and then wait about 20-30 minutes before shooting so when the insulin "hits", there's food on board......then 12 hours later you repeat the process
The only time it's really important that they don't have food is for the 2 hours right before shot times so that when you test, it's not a food-influenced number.....so take all food up for 2 hours before shot times
After those tests, it's OK to feed several small meals...most cats do better with mini-meals anyway because it's easier for the pancreas to deal with small meals versus big ones. You just need to try to get at least 1 mid-cycle test on the AM cycle and at least a "before bed" test on the PM cycle. Most cats go lower at night, so it's important to get that "before bed" test in at night so you can sleep without worrying if they're going to drop too low on you
Is the food Wellness canned or dry?