No need to be that exact, we measure night time depths using armlengths.
Use dob buoys cut in half or milk jugs, both rigged on 300lb mono with a longline clip to secure them to your wax loop at your desired depth.
In terms of weight, use as little as possible, in the GOM depending on your drift you may not even need a weight the light may be heavy enough. If you do, zip tie an 8-16oz lead to the bottom of your lp light. Light should be ~50' from your bait on a wax loop.
Hooks- 9/0 LP offset or 8/0-9/0 Mustad offset or 10/0 7691
Most people use too big a squid, 250-300gm ones are fine.
Use mono, not braid if you can.