Ioannis,
Yes, the registers are not permanent. The configuration needs to be written in to your pic code so the registers will be set on start up. The problem is there are 128 registers. I don't think they all need to be set. There are some with default settings that are OK as is. This is what I'm trying to figure out.

I know how to set the frequency. Give me your frequency band and I'll show you how. There is an online spreadsheet that makes it easy:
http://www.hoperf.com/upload/rf/RF22...s_RevB1-v5.xls