hero auto-spamming

Is there a way to force an AI hero to continually spam a skill, without having to manually put the checkbox on the skill everytime?

As a side question, Is gw still being supported with bug fixes/updates that the devs are actively addressing, or has everyone moved on to GW2?

No, but binding the particular skill to a keyboard key or additional mouse button (if you have any) should make forcing it's usage more convenient. You could also try reworking the bar in question so that the skill you want may be prioritised. Don't expect too much from heroes though.

Anet have stated that support for GW1 nowadays focuses pretty much entirely on account access issues. Unless there's a game breaking bug or something otherwise calamitous I wouldn't expect anything outside of that. They stated a long time ago (a couple of years now) that they were working on things like an Elona chapter of Beyond and a few skill updates but, again, I wouldn't expect that there's any active development on such things.