Most hardware stores will do 2 cuts for free. I have found if I plan carefully I can get them to basically do everything but shape the tombstones. Part of the secret is to already know exactly what cuts you want. (Then they will often do an extra one.)
Since it is hard to tell how the system is hooked up I would suggest checking it with a multimeter to determine the voltage and amperage of the LED you need. Then you can simply ask at an electronics store. My guess is you would need a 5 volt LED since the three batteries in series would put out 4.5 volts.
You are probably fairly safe if you are not charging for anything including entry into the haunt. It would carry the same risk as inviting folks to your home for a party. If you are charging then you will fall under your states food handling regulations.
Married with no children. Long time horror movie fan
Flying, chess and halloween
My love, sweet Queen and noble wife. I alone remain to bring delivery of your pain. Severed my darling, too quickly from this life. Of fires drawn and memories met, I shall hold our two hearts again in single time.