I have 2 questions.

1 is probably trivial. But I can't find the answer to it. Unlike other games I've played, Heroes doesn't have any kind of help (or maybe I just don't have it).
The point is: how do you move only part of the troops to garrisons and other mines? For example, there's a scenario where you need to bring a hero with a certain number of units to a tent. I calculated the number, but how do I make sure there are exactly that many? Or, if I want to leave, say, 2 dragons in a garrison, but I have 5 of them?
2nd question. Why does Faidaen need phoenixes if they are of no use (in the last mission)? Wouldn't it be easier to just build up the army?