Replying to Long exposure with stars, critique please

Alright so i tried a long exposure with stars to get the effect of the lines.

My shooting specs.

20 min shutter
F10

I pointed it at the north star so that everything rotates around that, but here are my questions.

1. how can i focus to get a crisp image when i can not see the stars when i look through my camera?

2. I know framing could be better but i tried to do it where there was no lights, so if i have lights in the picture(meaning a light bulb of a building), will that really screw over the photo or is it something i will just have to play with?

Thanks and any other critiquing is much appreciated!

Oh and i know i didn't post the photo, my photo up loader doesn't work but the photo is in my profile so is someone could embed it, that would be great, thanks.