Forum Post: Question regarding LNA CC259x

I have several questions regarding using LNA chip such as CC259x:

1. It seems to me LNA will also amplify receiving noise, am I right?
2. If we lower down Tx power and reduce Tx range by changing register value.  The receiving range should be the same as before or also reduced?
3. Following #2, changing register value can not change carrier sense range, right? If so, there could be impairment risk here.

Thanks

Rui