Does the MGM or Signature participate in any hotel or airline points programs?

Yes, MLife Rewards Program.

M-Life is accepted at MGM, NY-NY, Excalibur and Luxor resorts!

Yes

Yes mgm does participate in a points program it's called m life program

Yup, their MLife points can be earned at their various restaurants and in the casino, and be redeemed for hotel perks/comps!

Mlife Rewards

They have what is called M life rewards.