My nail girl always tells me that Gel nails are hard to get even. You know how the nail tech can sculpt the acrylic, and then file or buff it so that it takes the shape of your fingernail, and it's all smooth and perfect? Gels can't be buffed - they're put on, then they dry under a light, and that's it. They're hard to get even, and sometimes wind up with little high spots and low spots - like your nail is dented.
The white tips and American tips are just the tips they put on your nails to make them longer. When you're doing a french manicure, the nail tech can either put on a white tip, and then cover it with light pink acrylic (White Tips), OR she can use an American tip (translucent like your natural nail), and then put pink acrylic and white acrylic over it (Pink & White). If you like french manicure, you can start with a white tip, but your fills would have to be done with Pink & White, unless you want to have a new set done. If you're going to have colored polish on your nails, they will use the American tip, and then put acrylic or gel over it (Acrylic clear or Gel clear).
If you're happy with your acrylics, I'd stick with those.
Gels aren't any less damaging - it all has to do with the removal. Gel nails have to be filed/buffed off or grown out, and acrylics are soaked off. Either way, your nails will need some recovery time when you quit wearing them.
I don't have a clue what American Powder is.