this thread, I've been using a range of sources such as Adrian Goldsworthy's The Fall of Carthage. That's got loads of great info on when things happened and who the Romans were warring with.
I'm finding in some respects the slower expansion actually makes the game easier; you rarely get overstretched when you're not taking settlements every year. Although Spain is proving more difficult, the first army there has basically ground to a halt trying to keep Arse pacified.
Right now the Arverni, Seleukids, Sauromatae and Saka are on income support, with occasional help to the Makedonians and Getai.
For those I give regular tributes to, that comes from my own treasury.
Otherwise I don't leave money lying around. I'm extremely wary of hitting that 50,000 trigger where your family members start getting negative traits to do with being too rich. Most provinces are usually building something, and sometimes I recruit an additional army just to soak up cash. For example I have a stack in Sicily doing nothing, and one in Cisalpine Gaul which I keep using for reinforcements to those on the fronts (then replenishing it at my leisure).
I currently have five full armies now; one in Sicily, one in Cisalpine Gaul, one in Illyria, one in Spain and one on the way to Spain to speed things up there. I may recruit another one to sit outside Capua if Spain proves to zing the treasury up some.