The helos in ACOF take a little dedication to learn. Unlike the airplanes you'll need to spend a lot of time in a helo to get the hang of it. My advice is to try one of the virtual helicopter schools such as Hoversafe
http://members.shaw.ca/hoversafe/FlyingSchool.htm or Hovercontrol
http://www.hovercontrol.com/. Both will provide you with setup info for setting the sim and your controls to the optimum for flying the helos.
As for your questions. First make sure all your control sensitivities are set to "high" and with as little dead zone in the middle as you can get away with (preferably none but joysticks differ). You will also want to back the realism setting about one notch off the highest setting. Remember just one notch. Too far either way doesn't work well.
1. Just make sure you have the controls centered or if there's any wind that you have that countered. Now give just a little collective to lighten the bird and constantly keep making
small adjustments. It's kind of like balancing a unicycle on top of a tennis ball and juggling eggs (and I'm not kidding it really is ;D ). Just hover up for a few inches and try holding it there with no drift. For the time being I suggest that you just practice this much until you get it down perfect. If you start to get out of control you can ease up on the collective and set back down to regain control. Later you can keep increasing your height until you can hover up a hundred feet or so.
2. When you get good at #1 it will help you with this phase. Just hold the hover and ease down on the collective to lower. Remember though that when you get close enough to the ground you'll pick up the ground effect and tend to float. This is where you need to be extra careful not to drop too fast or start climbing again.