WHEN MANAGERS TAKE THINGS PERSONALLY AND SEEK REVENGE.. I have been employed by a big name grocery store for over 20 years. 1 week ago I punched in for work and 2 managers informed me I was suspended pending further investigation. They claim they did not

20+year veteran, model employee at big name grocery store. Current title Receiver, responsibilities in a nut shell I am the stores checkbook. 3 months ago with the permission of the "Boss" my 19 year old (not an employee) came in to get seasonal items ready to display. The co-manager became enraged when through the cameras viewed what she peceived to be, me questioning her authority etc.. I had punched out for lunch, heading to the backroom, and in front of vendors, sales reps, drivers (whom I'm in charge of) employees just laid into me. My 19 year old, quietly said good bye and left. The co-manager was livid, pacing, checking her phone, threatening that she was just waiting for confirmation of said permission. I'm standing there, she's just furious going on and on about company policy, union policy. When, she stops to take a breath I ask her "So, policies are only enforced when its to your benefit?" That's when she became confrontational, pulled up her sleeves pecking her head inches from my face saying "oh yeah!, c'mon let's take this outside!". Ummm.. "I'm out to lunch right now", was my response. Oh my, she was livid pointing in my direction saying "You've changed the dynamic of our entire relationship today, oh yeah we'll see about this. Oh yeah, man". She got the call back from our boss, yes I did have permission. Well know she was angry with me for intentionally making her look bad, that was her perception of it.
Back from my lunch she as calmly as possible talked to me about "what if something happened to her? what if? the store would be liable. I responded that in no way would I have ever done such a thing. From that point on she micromanaged every aspect of my job. She made it nearly impossible for me to get my day to day duties fulfilled. When I asked for help, she said absolutely not this is your job you get it done. I'm asking for help to sweep out the pit, to empty clean out certain areas, to have the floors cleaned, to assist with the conditioning of the backroom.
2 weeks ago my work boots were really aggravating my feet. I called my 16 year old to take my running shoes. In doing so, she wanted to ask to go somewhere. I said No, she got upset, crying saying I never have time to hear her out.. Long story, short: I felt bad she, since I still had backroom stuff to get done before I moved on to a different department, I called her back and she sat on a milk crate. I was working, she was trying to convince me to let her go somewhere, when I hand her some cups I was marking down and say something like "Here, put these on, today you will earn your gas $$". Or something to that effect. The co-manager was off that day, but when she found out, she looked through the store surveillance tapes, found the footage of my 16 year old in the backroom, and sent it to HR/LP or called. 12 days later I punch in for work and 2 morning managers inform me I am suspended pending further investigation, no reason given. Called my union rep, filed a grievance and it took 6 days to find out the reason for my suspension. Only to offered a settlement of: 1) Transfer locations 2) part-time [I earned full-time], but it hasn't been updated 3) as a cashier {code for punishment} It's within my same classification.
#1) Was my suspension necessary?
#2) If the burden of proof lies on the employer, shouldn't they have mailed me the reason for my suspension?
#3) My position and title places me in the exempt employee category. Only, I am not salary and I am union.
#4) Upon further review of California state labor laws, the proper steps leading up to my suspension were not taken. Or were they?
#5) My job performance has always been above expectations. I've not been written up, I don't talk back, I don't gossip.
#6) Am I entitled to back pay and interests, since this went from one pay period to another.. and currently heading into another.
#7) Isn't HR supposed to mitigate these incidents from blowing into epic proportions?

Also, I did not accept the offer through my union rep I have requested a meeting.. Which is something that I am unfamiliar with...