G'day William
In answer to your first question, remember that Sertorius was an exile on the run from Rome, living a backwoods existence in a fairly uncivilised part of the world (in those days), with a bunch of mates. The ability to field regular baggage is usually based on evidence of a well-controlled and organised logistical train, such that the soldiers knew their meals from day to day were being provided by the quartermaster's corps. To give Sertorius regular baggage would be to say that his logistical arrangements were more secure and organised than those of any Greek or Macedonian state, or of Carthage; that doesn't sound likely to me.
Turning to your second question, it's a tricky one. I've looked at the list as well, and never come up with anything which really satisfies me. How many points do you have to play with?
Anyway, having a second look, and things don't look so bad.
1. You're Aggression 0 and have compulsory Wooded Hills. This means you're going to be the defender a lot, and you have an opportunity to place a lot of terrain. This puts this army in the same category as my old fave, the Aitolian Hellenistic Greeks. This suggests you want to take quite a few Ps (S), although the 33 minimum is probably quite enough. This also suggests you may want to take the Ambush stratagem - might as well keep opponents guessing as long as possible about where your army is, and perhaps the Concealed Command one too.
2. You won't be able to cover all the table with terrain, so you'll need some stuff to fight in good going, so the Bd (O) are important, though the Ax (S) will be useful here too.
3. The Expendables will be useful for dealing with nasties like Knights. However, to make the best use of them, you'd probably like to have the Unusual Weapons stratagem, to make sure you get to place them where you want them.
4. Your army actually has the troops to deal with most other troops, as long as you have the PIPs. Therefore, I'd strongly suggest you consider regular sub-generals, to increase the chance that active commands will get the PIPs they need. A good PIP supply increases the chances you'll be able to send spare elements onto enemy flanks, or spare groups into the enemy's rear in anticipation of causing later mayhem. This is where a Brilliant general's ability to double PIPs is so useful - it pretty much delivered me victory in two of the games I used it at Cancon. And if you have regular sub-generals, you can double their PIPs, which you can't do if they're irregular ally-generals.
5. You may also wish to consider the Scouts stratagem, as a counter to an enemy using it. If you deploy more scout elements than your opponent, each of his scouts dies on a 1 or 2, rather than just on a 1. This is a very cheap and easy way to destroy enemy elements.
6. Upgrading the Ax or Cv to Regular might be useful. The extra march available without PIP penalty to Regulars is pretty darn useful, and they'll be a little easier to hold if they either break or want to be impetuous.
7. You might like to consider a 4th (Spanish) command under an ally general. Consider this: with three regular generals, each with irregular command baggage, you'll only have three PIP dice. The rules require you to roll four PIP dice, with a dummy dice if necessary. But if you have a lot of terrain on the table, and perhaps bulk up your visible troops with the Exaggerating Numbers stratagem, you may really paralyse your opponent: Are the troops real? Is there a command flank marching? Or is there an extra command, but on table and Concealed?
You'll see I've recommended a few more stratagems than you can actually use in a game. On that basis, I'd consider dropping the flaming ox-wagons, as fun as they sound (and I bet they'd look great too!). It frees up the points to buy extra troops or to upgrade some of the Spanish to Regular. In any case, I suspect most people will expect you to bring the ox-carts, and so may be tempted to waste PIPs looking for them. Yes, it makes it hard for you to take on Knights, but against most armies you'll have other troops you can target.
If you go for three commands, I'd suggest the C-in-C have all the legionaries, a couple of Cv, a couple of LH, a couple of Ax (S), and a few Ps (S) and (O); the first sub has the rest of the Ax (S) and a couple of Cv, LH and Ps (O); the second sub has just Cv and Ps (S). PIP dice allocation would be C-in-C gets highest, first sub gets middle and second sub gets lowest.
If you go for four commands, keep the above structure, but add an ally command which is as small as the rules allow, plus baggage (Ally, 2 Bg, 1 Cv, 1 Ps (O) and 11 Ps (S), for a total of 15 ME). That command would probably flank march most times, into bad terrain, with the intention of making the enemy nervous about protecting his baggage.
Recommended tactics: Try to be the defender! ;-) Place lots of terrain. Use it to place ambushes which will pin the enemy in his half of the table. Be aggressive with the legionaries and use flank threats from the Ps to allow you to take on the enemy. Use Sertorius's Brilliant Strokes to double PIPs, especially in the first bound, when you may be able to get large numbers of troops a long way across the table and upset your opponent's plans.
Recommended stratagems: Probably Concealed Command and Exaggerating Numbers.
Of course, talk is cheap, and I can't guarantee my suggestions would work. However, you've inspired me to have another look at the Hellenistic Greek list, to see if I could make an Achaian League army under Philopoimon work in the same way I've described.
