I think the Jury is still out on the catch can. MAP feels that one isn't needed but other trusted vendors currently sell or are designing them for this platform so I don't think anyone really knows for sure on that issue.
This engine is direct injection, not a combination. There are some manufacturers that do both, Toyota is one I believe. They have 2 fuel injectors per cylinder. The civics have one injector that sprays into the cylinder (DI) it is just angled to partly spray on the intake valves when they are...
I don't think that issue is specifically related to the ktuner, because my Si did it with the stock tune. It would bounce around 500ish rpm at idle and mine was intermittent it didn't do it all of the time.
Considering that California is more restrictive than the other states I would assume it is legal outside of CA if it is legal in CA. I don't really pay attention though since I live in FL and we do not have inspections here.