I've seen Rvs park there overnight sir but this walmart is a 7 day a week store but not a 24 hr super store it closes at around 10 pm.I wouldn't recomend staying there more than one night unless you talked to the management at the service desk sir.
Yes all Wal Marts allow this
Not sure but I have noticed that 18 wheelers park there over night. I know this probably doesn't help much. Maybe you could call and ask. Sorry I couldn't help anymore than this.
Thanks! Your answer is awaiting moderation.