You will need a lot of RSS subscribers in order to earn any serious money. I would say 1000-2000 subscribers would be the bare minimum.
Nope and I don't think that anyone ever will to be perfectly honest. Think about it - RSS users are very tech-savvy, and we all know that the majority of these people don't generally click on ads. I think it would be wise to focus your money-making efforts elsewhere.
The problem is that RSS subscribers are mostly bloggers themselves or someone techie (and most of them don't click on ads)
i was curious on that too if you can earn from adsense on feeds, now I know, ill just focus on the site.