No it should not cover the speaker... any good protector will have a cutout for the speaker AND cover the home/soft keys. If you feel you need a protector (I use one) then spend the money on a decent one:icon_ devil:
Personally I recommend the Crystal:
SGPStore.com | Protector skin for your iPod, iPhone, MP3, cell phone, notebook, and more handheld devices
I always wondered that myself, but never got into screen protectors. I guess I don't see the point, the screen is made from gorilla glass and is pretty unscratchable, right? What are you protecting against?
uh.... NOOOOO!!! It scratches just as easily as any glass. If you work/play outside or around fine particulate(s) than a screen protector is mandatory. If you have a desk-job and are fairly inactive you're probably fine w/o one. Any type of sand or silica will easily scratch it so where/how you keep it will also be a factor (e.g. if you keep it in your pocket you should protect the screen).
Just search, you'll find tons of posts by people that have scratched (and broken) their screens... It amazes me how easily people by into marketing... especially product names.