Hi Scooter,
Welcome to the 12" club
1. Focusing the Finderscope:
You will notice that the front of the finderscope unscrews (the black bit) and also has a lock nut section. Just unscrew, or screw in, the black section, then when stars look focused turn the lock ring against it. That will hold it there.
Tip - If you need to screw the focus section towards you, (screw in) screw the lock ring in a fair bit so it doesn't stop the focus section from screwing in. If you need to screw the focus out, no problem with the lock ring.
2. Planets zooming across the Eyepiece:
Use a lower magnification. Yep, the planet will look smaller but you'll be able to follow it with the scope a lot easier. After a while you will get used to how the scope moves and you will do it automatically. Then you can bump the Magnification up and be better at following it.
3. Tracking with a Dob:
Yes it can be done. You will need to buy or build a Tracking Platform.
Those that know about them will help you further.
I hope that is a start for you
I don't want to give away ALL the trade secrets in one post
