Two things:
The battery cover, as indicated before, is flexible. I remove mine almost daily (to swap batteries). It's still going fine. Only issue I've heard about is the HTC sticker-logo peeling. I use a case anyway (although a Seidio, which also peels).
Secondly, the reason Verizon listed the SD limit as 16GB, initially, was because Android 2.1 devices could not format a 32GB card. You'd have to format them using a PC (FAT32) for use within an Android phone. Not sure if 2.2 fixed this issue, but almost all modern smartphones can take a 32GB card.
Phones that can use MicroSD but not MicroSDHC are limited to 4GB or less. Phones that can use MicroSDHC are generally limited t0 32GB with some exceptions. Phones that will be built to use MicroSDXC will go up to 4TB. Even one of my older phones which was listed by the carrier as supporting "up to 8GB" will take a 32GB just find, since they're both MicroSDHC. Carriers have a habit of listing the max current SD size rather than what the phone can actually take.