My wget -O-
http://IP_P2POOL_SERVER:9332/patron_sendmany/5.0 returned a lot of addresses with some amount which, theoreticaly, should be payed to those addresses. But my initial setup _has no_ funds.
If I`ll schedule cron to make periodical payments (when only my miners are connected to the node) then, after a while (when my miners mine sufficient amount of BTC) my node will send those sums to the foreign addresses?

Why?
Thank in advance and sorry, if my questions are a bit stupid - I just want to understand complete scheme

"Why" is because if you do this, you are making a one-time donation to everyone who is mining on p2pool. Some people used to donate funds to miners when p2pool was young to encourage early adoption. You need to have funds in your wallet first if you want to give them away.