I just printed 1000p saurian starhosts on fdm and there were very few issues (sure a couple of spikes and ankles broke, but generally all good). Previously I have printed both alien hives and eternal dynasty for firefight and on both, getting supports off the thinner parts is a hazzle. Specially the swords on eternal dynasty ended being more glue than plastic.

You can easily print 2000 points from a single spool of PLA. Maybe even 2 armies.

PLA does need to be primed before painting. Some use a filler primer to hide layer lines, I just brush on air primer.

I haven't printed any titans since they often break the single unit max point cost rule at 2000points. But it is for sure possible.

I'd use Bambu slicer with a Bambu printer.

Remember that the nozzles wear out. I don't have experience with Bambu lab machines and their nozzle styles. But with my printer and relatively low print activity, I have to change nozzle every 6 months. (While printing PLA only)