Is there a limit to the range I can set for the bots? Are there any realistic vs technical limitations? I imagine I can set the number to whatever I want, but I worry that expanding their range too much will break things. Thoughts?
There's no hard coded limit in the plugin.
If your roam range exceeds the boundaries of the map then it'll never be triggered and the go-home code won't run.
I think the AI might have its own range+return built in at some high number; Can't remember for certain.
Either way, worst case scenario is they'll free-roam the map.
I'm not entirely opposed to them free roaming, to be honest. Are there any server performance issues I might encounter? I'm considering doubling it from 40 to 80 (or higher) just to give them more chance at running into players.
I don't think there should be any performance impact.
If you want free-roamers you could use the Biome profiles?
I use them already, but maybe I'm misunderstanding their usage. Do the biome bots wander freely? Does the biome bot spawn number (5 by default) indicate that only five of them at one time will spawn on the entire map?