Hi,
Ok, 3 days isn't a lot, and you should simply "bump" your question on the forum to get attention. Publishers are very busy, so sometimes it takes days to get a reply, don't think they try to ignore you, it's difficult to keep up.
Yes, Pool Manager is supported for PlayMaker via our community, on the wiki:
https://hutonggames.fogbugz.com/default.asp?W839So you'll have all the actions you need to spawn, and despawn from pools. But you question seems to be more about waypoints. So it depends what waypoint system you are are using, but in all cases, that system will have a way to tell you that a gameobject reached a waypoint. If these waypoint are custom and you built them, then you'll need to use "triggers" quite simply. Once your ennemy enters a waypoint trigger, you despawn it.
As for your errors, it seems a problem with the way you setup pool and use them, it seems you have really yet grasp how pools work, so I would read the doc and inspire from existing samples before getting back to this, it's very important.
You can delete that part of a code and switch to PlayMaker, but you need to make sure that your waypoint system has PlayMaker support somehow. I know this one has for example:
https://www.assetstore.unity3d.com/en/#!/content/2506 but there are many mores for sure.
Bye,
Jean