1) Most Antminers (including the S4, S5, and S7, and possibly the S3) have problems with p2pool, and will lose hashrate and become unstable unless you use a special firmware. These problems were fixed with the S9, but during the earlier generations, p2pool lost a lot of hashrate.
I've used a dozen S1's and one S7 with P2Pool and haven't noticed any lost hashrate. Is this an accepted thing? Should I be looking into that special firmware?