The steem miner´s question

Hi,
I started to mine yesterday, with some comunity help I set up everithing and it works.
I chceck my balance saying:

0.000 STEEM 12709.198402 VESTS 0.000 SBD

What does it mean and mainly what can I do with? How and for what can I use VESTS?

But later I checked was the same. Is it true just Witnesses can get rewarded from mining? If yes how to be Witness(is it ok that rabbits 0-60 are everywhere-waiting lists... and so one)? If not where when my mining reward will appear?
Is there any ..pool.. option if it is like just 100 Witnesses can be rewarded?

Thanks, for everyone for help.