If you buy 1 battalion you'll have all the leadbelchers you ever need... so with 2 battalions you certainly wont need to buy any more individually. When I do use mine I either go for 2*2 or a unit of 3 (either way with a champion- only unit that always gets one- its enormously helpful with wound allocation). I only use 4 and even when I come round to the idea that they cant be as bad as I remember I still never think of using more.
Maneaters are great models and I suggest you get them all. There are only 6 different ones (araby, ninja, pirate, female, paymaster and empire) and they all look really great, though I tend to make more use of them as bruisers then I do as maneaters: I use the female as my 'matron' (tyrant) since she almost always carries the tenderiser (you know its right

) and the paymaster as a paymaster (BSB) since no ogre would dare run away with their payment on the line. Occasionally the araby maneater gets used as a challenge monkey since his ironfist means he has a pretty decent armour save, although it does annoy me that 1/6 maneater models is armed in a way that mens he cannot ever be used WYSIWYG (there is no ironfist option for maneaters).
My standard unit is pirate, ninja and empire/female when I run maneaters. I say the ninja has got throwing stars (which he does) which count as a brace of handguns so have 4 S4AP shots a turn but am still backed up by S7... although other players would just take cathayan longswords and charge into combat (I do the same normally- the shooting is just to persaude mages to stay inside units so I can trap them in combat).
I suggest you get a slavegiant as well at some point- they arent the best unit around but they are good fun, and they will do very large amounts of damage to almost everything (plus falling over is now supurb- S6 no save D3 wound hits on everything under the template). You'ld be surprised just how big the grims both players wear when a slavegaint picks up the enemy general and puts him down his pants- a very ignoble end :laugh: Plus now he can thunderstomp, so the most likely outcome of being in a fight is 2D6 S6 hits on the enemy, which is fairly nasty (and should see him through most units around that dont have characters in). He is nice and cheap as well, so although not as good as other giants in ocmbat he does make the best bullet magnet out of any giant (they draw an inordinate amount of shooting/magic).
Other then that you are pretty much sorted, and would have an army similar in size to mine (although mine is a little more fleshed out). Hunters, trappers, Skrag and yhetees are all good fun in their own way, but they arent really needed to make an army... in fact other then Skrag I think they would only weaken most people's armies.