So is there any way I could lower action on my acoustic by myself, or would I have to take it to a shop?

^By bridge, i think they mean saddle. Sanding it down is one way to achieve a lower action or you could make the grooves in the nut deeper. If you have any doubts about doing it yourself though, i recommend taking it into a store n getting a qualified tech to do it. Its inexpensive n then u wont have to worry.