I ride with a coaster brake, but would recommend rim (hand) brakes. The coaster has got me a little nervous at times; but the bike is not a daily rider nor is it neccesary transportation at any time....just for fun.
I also like single speeds (or very few gears), as I think it looks better, frees up the handlebars a bit, drops weight, is easier to maintain, and if you get a good gear ration you shouldn't have to pedal too hard or too fast to get 'er started or if she dies and you gotta pedal it home.
You can add rim brakes real easy and they're not very expensive. I used these (Link) and they work fine for the way I ride. Most of the cruiser frames already have a hole to mount them both in the front and rear.