Nice new wallet syncing atm and bought an extra 1 million leafs!

Could someone tell me in short what the following new features/changes are?

- p4f ( tested, diff nodes, works ) ??

- digishield ( tested, adjusts every block and is equal to digibyte solution, works ) ?? new diff algo?
replacement for KGW, as KGW was still exploited a bit

- alert system updated ?? alerts what?
so we can message users from the wallet to tell then when theres a update needed

- flat rewards ( tested, works ) ?? what does that do?
stops multipools grabbing just the high blocks

- higher coinbase maturity ( tested, works ) ?? why is this better?
coins mined cannot be spent instantly

- merge mining ( almost implemented ( tested, works mergeid=77 ) ?? merged mining with which coin and how?
it means users can mine other merge mine coins at the same time for a small chance of also winning on the other coins chain, but helps secures our coin.