I see a 50LM "US lower 48 lifetime maps" in a 2nd hand shop with a mount. I need some quick and dirty.

1- can the mapping region be expanded just by putting maps on the sdcard? (it has a slot)
2-if so, can i just put an unlocked map in root \garmin to test it? will it display without the jvc's and such?
3-if that's okay, will the usual CNNA maps with these supplementary files (jvc, asr, etc) work in this or is it different?

it's $35 so i don't think it'll last.

thanks...