Mineral rights leasing help in Oklahoma County


My mother in law recently found out she has mineral rights to 50-ish acres in Oklahoma (34-11N-1E in Oklahoma County). I think it's a portion of a 160 acre plot that was split among some children. She was recently contacted to lease her portion of the land for $50 an acre bonus, 3/16 share, for three years. I had a few questions since our family is fairly new to all of this. Any info would be much appreciated!

1) Where can we find what nearby plots of land are leasing for? Is this public info? $50 an acre seems low just based on reading replies in this forum. They also offered $75 an acre for 1/16th share.
2) If she owns a piece of the 160 acres, can she lease to a different company than the other person did who has the remaining mineral rights on the land?
3) Can local records be updated with more recent names of ownership? So that a land man doesn't have to go through so much trouble contacting my MIL next time... They actually contacted my wife through Facebook to get a hold of her mother.
4) Lastly, since she has owned these mineral rights for many years (decades, I'm assuming) and has never been contacted about a lease, should she do any research to see if anyone was using her rights without her knowing? Not sure if that happens or not..

Thanks in advance!

You need to hire a CMM or an attorney. Take no less than 1/5th.