Battle Droids
The backbone of the Neimoidian army, Trade Federation battle droids are the perfect example of Trade Federation philosophies: they're mindlessly loyal, cheap, and they make it so that the Neimoidians never have to fight for themselves. The distinctively-odd body configuration of the battle droids was envisioned by Neimoidian designers as an emulation of skeletal Neimoidians (the Neimoidian brain sac deflates after death, and the body withers into the bizarre paraody of life that the battle droid resembles). Although this psychological ploy works well among the Neimoidians themselves, it is largely wasted on other sentients, but the droids' fearsome combat applications more than make up for this failed psychological tactic.
Battle droids are deployed into the field in number of ways. Small squads can be deployed for security reasons, or riding STAPs for recon missions. At their most terrifying, battle droids are deployed en masse via the use of massive droid carriers, which can deploy hundreds of the nasty mechanicals in one fell swoop.
Because they are designed to be cheap and easy to mass produce, battle droids aren't all that hardy; allthough mostly immune to weather (though vulnerable to immersion), they're fairly fragile. The operative tactic in using battle droid armies lies not on the individual soldiers' abilities, but rather in using the "maul and overrun" tactic. Even though they can be dismatled with primitive hand-to-hand weapons if hit hard enough, a few hundred battle droids with blaster rifles are still no laughing matter. With that many guns to fire, NO army, no matter how fragile, is anything to sneer at.
Large masses of battle droids are guided in the field by remote communications from orbiting Trade Federation command ships; the battle droids' brains are not very advanced, so as to avoid developing personality traits of any sort (and, once again, to keep them cheap). In smaller groups, certain slightly more advanced battle droids act as officers, and are capable of understanding verbal commands given to them by authorized personnel and then ordering other battle droids to carry out those orders. Although battle droids have a rudimentary ability to process data on their own, they are notoriously bad at it (one job is about all they can process). Battle droids with programming for specific purposes (transport pilots, security functions, etc.) are physically no different from their counterparts except for their painted markings.
Battle droids will only retreat from a losing battle or potential danger when they have been specifically ordered to do so. Small groups are often given self-preservation agendas to help maintain their limited numbers in the field, but large deployments are seldom allowed to act thusly.
GMs should feel free to have fun with battle droids...they are dumb and numerous (even more so than Stormtroopers!) and should be handled as such.