Don't bother helping the Julii out if you can't be bothered with Warbands. Let them get stuck in, they should be fine - unless you want to control the cities they want. You don't have to do every senate mission either, and some are just too unfair (blockade a port miles away that is guarded by 2 giant Pirate fleets... get stuffed you toga-clad snobs!)

Warband armies are pretty annoying, but so easy to kill for the most part. Your Hastati and Equites are more than a match for them as you would know. Just place a load of forts on roads between your settlements and in narrow passes and stick a unit of Town watch in there. You can move units across the network of forts relatively safely, and the forts can slow the Gauls down as they ponder whether or not to attack them. It's the Egyptians that are the real pain in the butt. Their stupid chariots and archers, plus all that plodding around sand dunes is a tedious business.

As to the 25 provence thing and the Senate turning on you - I've reached that mark and there's no immediate signs of any troubles. Build up a garrison in Italy if you're worried, but you have Sciliy to launch attacks from should the Romans decide it's time to take chunks out of each other.