Can i poach position coaches? Meaning can i offer someones RunningBack coach to be my Secondary Coach? What qualifies as a promotion positition wise?

No, you can only poach when offering a promotion. You can take someone else's position coach, but only if you make them OC, DC or HC.

So after the first off season i'm pretty much stuck with my same garbage position coaches? lol some are in the 50s and 60s and i dont want that. But nobodies coaches are gonna be off contract at this point

You can fire coaches. Granted that doesn't make better coaches available however I have heard coaches are important for playbook more than their rating.

I "think" it works like this:

HC = playbook
OC/DC = overall player development
Position Coaches = player development for the position they coach.

Hiring other coaches automatically fires the current coach in that position.

Others can chime in on who does the in game play calling and if any of the above is correct.

If you are worried about low rated coaches, pick one that is trending up. Coaches have progress ratings like players, and some go up while others go down. I prefer coaches who increase 2 points a year or more.

Appreciate this, i didn't even notice they had trends. I'll do this for my two lowest coaches.

The play calling comes from the HC's playbook and your sliders set for play type and personnel.

The only thing I would add to what you have above is that I believe the HC's rating also factor into player development.

Just sign the coaches you wish to retain to a 6 yr extension + whatever$ (think thousands; though many use 1$ but i'm paraniod lmao) at efa 1.
IMO, an important fix is allowing teams to make a counter offer for coaches getting an offer. It should not be a 1 sim negotiation. The coach is under contract and RL NFL rules require the negotiations to be disclosed to the team holding the existing contract.
Better: We should be allowed to simply say "NO. You can not" as what occurs in the RL NFL.
You signed, we say nope. Shaddup.
Let them be livid!

Edit: If you are the poacher (it happens) coaches under contract can only go upwards. Position coaches can only become coordinators, coordinators can only become HC.
#nocakes and no lateral movement allowed.

2nd edit: you can fire a coach and rehire them at a lesser position. Use at your own risk.