Google Voice – Setting Up with Your Phone Number

1 + 3. Your method should work. See here. (The comments indicate that it works for calling people too)

1. I believe that there isn't another way of figuring the numbers out.

I would note that there are some google voice native apps already back in the app store, as well as the official Google app is said to be on its way.

Google Voice voicemail works on your cell phone by setting up conditional call forwarding. All the settings you put in your phone made your cell phone carrier forward any calls you do not answer for any reason, (phone turned off, you hit ignore, or you just let it ring) to your Google Voice Number.

When this happens Google Voice treats that call like anyone else calling. It will ring all of the phones you have listed and checked under "forwards to:" on the phones tab in your Google Voice settings.

If those phones go unanswered it then sends them to voicemail.

The main problem I have with that is when someone calls your cell phone it rings say 4 times, then forwards the call to GV which rings your home phone 4 times, so your caller hears a lot of ringing, and at least in my case hang up before actually getting to my voicemail a lot of the time.

It is nice on one hand, if someone calls you on your cell when you are home you can just hit ignore on your cell, and it will automatically ring your home phone, and you can take the call there.