Second question first...
What do YOU want? A reef tank limits the fish you can get, as many of species of salt water fish out there are not reef compatible. Plus, even more fish are not invertebrate compatible, as snails, crabs and shrimp are on many fish's menus.
Personally, am am interested in the diversity of coral, and the colors of coral. While I do miss my puffer and a Humu Humu trigger, I like my reef tanks more, as I see all the interaction between fish, invertebrates and coral.
As for glass versus acrylic, that is the age old question. You will fins proponents of each. Acrylic is lighter and more flexible as far as design. The trade off is that it scratches easily. Scratches in acrylic can be "buffed out" but it is a project...
Glass tanks are heavier, and a pain if you want to drill a hole in. They do not scratch as easily, but they can scratch (if a rock falls and hits it, stuff like that) and those scratches are much harder to get out.
Hope that helps! Go to the "New to the hobby" forum, and there are some stickies up top that will point you to a LOT of good information. Plus, this group is also friendly and helpful...