1) With the current 5.11 version of Eagle, you are limited to the one vector font. There may be some ULP to change that, but I didn't look for it. Check user groups and on the Cadsoft site for user contributions.
2) Your polygon would be in the signal layer in which you want the text to etch.
3) Polygons are very useful. You are allowed to have various priorities. If you are new to Eagle, it is tempting to use other geometric shapes and just fill them to "look like" large signal areas. BUT, they do not become signal layers and can create problems with DRC, routing, and when you also have a polygon fill. Polygons can be named signals, are recognized as signals, and don't have the aforementioned problems.
I think everyone who has replied to this thread will agree that it is worth an hour or so to get comfortable with polygons.
John