If i understand it correctly a real bitcoin block that was found by a p2pool miner cant be stolen by him because this block already includes all the reward transactions to those miners that mined on that block. So a miner has to decide upfront if he wants to mine p2pool or solo. Deciding to change this wont work after a block was found.
Yes.
That means the reward 25BTC + fees is created and in the same time these newly mined bitcoins are broken apart? I didnt think this can work because the actual block only brought this coins into existence but at the same time is splitting it. But it seems to work then.
The "coinbase" transaction is just like any other transaction, except it has no inputs. There is no problem with it have 1000 outputs, as long as the block is less than 1MB total.
What i meant regarding the reward. The split of the reward among all miners means that the newly mined block is not having the newest data. Up to the last 10 seconds of mining of others can be lost because not already included. 10 seconds are a good choice then to minimize this i think.
It is a random process. Failed hashes aren't saved up or something.
The last 10 seconds was used to try to find the block, so it wasn't wasted. Ofc, only 1 miner actually found one.