2) The p2pool does adjust share difficulty, but on a global basis. So with just my miners attached, everyone who connected will see about 1k share difficulty, which is again problematic for small miners.
I suppose you mean the difficulty for each worker, since it reads like node-basis (i.e with your miners...).
Actually everyone can adjust this by append the number they want to the username (address or not),
for example, 13qnEgPTxJW6mm88dLpnHXZyryN5EXBciq+16
But I think it just make the graphs looks nicer for small miners

Ah, didn't know that. But that auto adjust to something to keep the graphs pretty would be very nice.