The best way I found so far to get the same functionality is to:
call find_entities_filtered and iterate through the returned entities, setting .active=false on all of them.

Is there a way to stop/start beacons emitting their effect?
I've tried using the LuaEnitity.active value, but all this does is stopping the animation of the beacon entity.

If there is no way to enable/disable, is it possible to change the effectivity, like LuaEnitity.effectivity_modifier for cars?

I was afraid of that. Thanks for confirming it.

Say I want a technology with a prerequisite of mining-productivity-10. Is there a way to reference the "level" of the infinite research.
Or do I have to add technology entries for mining-productivity-4 to 10?