A newbie question

[lillumultipass]

Hi everyone!
I am new to D2 (just started playing the demo) and to this forum...on to my question: I have read some reviews saying that there was a lot of micro management involved in D2; after a few turns into the game, I am starting to understand what they meant; do you have some tips that could help "reduce" the workload; because I only got a handful of provinces and 2 fortresses, but I canno't imagine how "painful" it should be in the late game...
Oh, and BTW I was just wondering something: sometimes, I try to buy multiple of a nuit, like a Jotun Gode, but I can't, even though I have enough ressources and gold; is there any kind of limit???
Thanks for you help!