I-485/131/765 was filed Aug 7th, I-130 approved on Sept23rd. Any reason why EAD I-131 is not approved yet?

Yes

H1b visa stamping in abroad

You should be able to use the H visa to enter the United States with the approval notice from the new employer. You should consult with the...

Going to a Trip Outside of the US and Coming Back Having a Green Card.

GC and Passport.

10yr ban was over after deportation due to denied I-751

You should hire an attorney to assist you as this is a complicate area of law.

What is the procedure to withdraw/cancel the H4 extension?

Send a letter to USCIS requesting same.

Is J1 waiver needed if I am a Canadian citizen? Can I go to H1 visa directly? Are there any special requirements?

You should consult with an experienced immigration attorney to careful plan your steps toward permanent residency.

I am 46 and my boyfriend from Kosovo is 22.We want to marry. Will there be a delay in his paperwork due to our age difference?

Probably suspicious but not impossible to overcome if its a bona fide marriage for love.

Do I need to bring my mom, the petitioner for the I-130, to the interview?

The petitioner needs to be present. I would speak with an experienced immigration attorney.

I would not travel without the GC or stamp in the passport. But be patient it will arrive.

Time to hire an attorney, if you don't have one.