When I went to buy my first guitar, I was planning on buying an electric, but the owner of the store convinced me otherwise. He told me to buy an accoustic first because switching from an accoustic to an electric is easier than the other way around. ...
It won't hurt the amp. You'll be able to hear the bass guitar just fine. You want a real bass amp if you're playing with a band, you want the bass to 'punch through'. But then you'd probably want something bigger than 15 watts. Years 'n' years ago I ...
The main trouble you'll run into is if there are any electric tricks that can't be done on acoustic, because it involves doing something that sounds great through an amp. You may not recognize what's not possible on an acoustic. But except for those ...