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?

- alert system updated ?? alerts what?

- flat rewards ( tested, works ) ?? what does that do?

- higher coinbase maturity ( tested, works ) ?? why is this better?

- merge mining ( almost implemented ( tested, works mergeid=77 ) ?? merged mining with which coin and how?