1) Range varies on what internals you have, but it's obviously going to be much shorter than a real bullet. It's just the way it's designed. There's really no possible way to make it go further with BBs since they are round in shape.
2) Most veterans and people who are experienced in airsoft will treat hi-caps as taboo, and most milsims will either limit hicaps, or ban them outright. It's mostly appealing to newer players who just want to spray all the time.
3) If you want recoil, go for a gas gun. Most people don't like them because of the amount of maintenance required and drawbacks, but they're really fun to use.
4) It's just another drawback to how AEGs are designed, can't really fix that.
5) I can't tell if you're talking about gun variation, or hicaps, or both...but there's a lot of different gun models and manufactures out there, just gotta dig around. Hicaps I've already mentioned.