Epeiros will have their king Pyrrhus general of a small elite army in Taras. Pull your 4-unit army out of Beneventum and just across the border to Roma but close enough that Roma garrison will reinforce if the army is attacked. Let Pyrrhus take Beneventum as it is now undefended, and use the garrison to kill off his important troops, like his Elephants and/or cavalry. Recruit 6 units per turn for the army near Rome for 2 turns to get: 6 principes, 2 triarii, 2 accensi (slingers), 2 equities (cavalry). So 6 units in the first turn of the game, and then 6 units on the second turn: This should make that a 16 unit army (4+12). You can also hire a couple of mercenaries if you like to get to get almost a full stack army, but I don't think that is even necessary to defeat the Pyrrhus army, especially if you took out his elephants and cavalry with the Beneventum garrison, but you should have the coin to hire some mercs if you want. Recruit a couple of units for the army in Cosentia too so that it will be strong enough that Pyrrhus won't go after it. Now on the third turn you retake Beneventum with the army near Rome.

From there you can make the Cosentia army meet up with the Beneventum army on turn 4 and then besiege Taras on turn 5 and should be able to take it on turn 6 or 7 with siege ladders.

The Etruscans may send an army to besiege Rome, so you may want to raise a small army with just a few principes and perhaps a few slingers. That will be enough to make it impossible to take Rome. They MAY go after Ariminum or Asculum instead, but it's not really a big problem to retake if they capture it. In fact in that case you could go after Arretium, which have no walls as defense, which will take away their best ability to recruit units as them capturing either Asculum or Arretium is worse for them, and so finishing them off thereafter should be piece of cake, same for the Epeiros capital Appollonia, their last region after you take Taras. You can choose to satrapy Epeiros here if you like so that you won't have to weorry about protecting Appollonia and they'll also provide a bit of nice help against Carthage later on.

After defeating the Etruscans and Epeiros it could be time to look at Syracuse and Carthage. Carthage probably have not been able to take Syracuse yet. But first you should focus on consolidating your territories:

Build up your economy in your two provinces: Latium (Rome) and Magna Graecia (Taras), and enact edicts. Magna Graecia can be a great food region, providing both much food and income from agriculture with the right buildings, and later you can switch away from food and focus mainly on the agricultural income which can get really high eventually with the right build. Slave market building is a good pick for Taras as it boosts income from agriculture while increasing the tax from slaves and decreasing the unrest from slaves. I actually suggest building slave markets in ALL province capitals, no matter the specific provinces other build focus, as it gives HUGE tax income from slaves when slave pop is at max. To offset the unrest from high slave pop and because you get so much tax from slaves, you'll eventually be able to run your empire on LOW tax rate at all times, which is great for increasing populations, growth and party loyalty.

Example of Slave tax impact (With Slave Trader III and Sell Slaves edict):


A very important early source of food is the Fishing Port II port building. It's cheap, fast to build and it already gives 5 food and NO negative PO or squalor.

Fishing Port II: