- I set a 1% pool fee, meaning that if somebody on my node mined a block, i would get a 1% cut... Seems fair. But i've also seen a node setting a +90% fee, does this mean that he gets an equal cut when somebody on an other node finds a block, but when he finds a block he can keep +90% of the block reward?
It is only the percentage of the particular address's earnings, not the whole block reward.
- i can setup my node so it doesn't broadcast new transactions. If i do this, can i put my own (secret) transactions in a block or do the other nodes also have to know my transactions? I know the chance of hitting a block by yourself are astronomically small, so it's just a theoretical question.
I think the short answer is, yes.
- Can i prioritise my own transactions, so that if a block gets mined on my node, my own transactions have a better shot of being in this block?
How is this different than the last question?
- If i find a share at a time when there is a dip in the p2pool network's hashrate (so the diff of the sharechain is lower), does this share have an equal value to a share that is found at a time of high hashrate (so high diff)?
Yes, p2pool is PPLNS regardless of the current difficulty. If the difficulty is high, you find less shares and vice versa.
- I tried a setup where i merge mined several coins, the log didn't show any errors, but for some reason i didn't find a single share on the BTC sharechain anymore (at the time i should have found 6+ shares, but i didn't find a single one... This could be due to variance, but the odds of this should be small). Is there a potential pitfall i missed when setting up merged mining, or was i just very, very unlucky?
There is not enough information without your logs to answer this question.