Hmm...ill try to help u as much as i can...
1.) Angelfish are a really neat species, they get about 5-6" though
2.) Angelfish fit this perfectly...they get a swim style and personality of their own.
3.)Silver Dollars go good with angelfish...along with mollies....
4.)
5.)After your tank is fullly cycled, test your water about every 7-10 days for nitrate. When it starts getting high, do a 25% water change.
6.) I would start with the more aggressive fish you buy first then put they least in (i think thats how it goes)
7.) Live plants are beneficial to your aquarium because they use nitrate, increasing the time between water changes. Most fish like live food...i dont know about black worm though.
Hope this helped.