Can I change from J2 (which is subject to the 2 year home residency requirement) to F1?

Thank you! Yes. But other types of status (H-1B) no unless you get a waiver.

Sponsor my partner after my Green Card

PDs now take about 2 years (though it may change).

How can I get another green card?

Can do an I-130 then IV consular processing.

Employer (manager) is giving too much work that is not feasible to complete in the given schedule.

I was on H-1B before and had to work harder too. That’s how it is. If you get petitioned for permanent residency it’s worth it.

AM I APPROVE UNDER CSPA LAW ?

b. Age at time priority dates became current minus pendency of I-130 petition. Make sure beneficiary sought to acquire immigrant visa within a year.

HOW TO KNOW IF I AM ELIGIBLE TO GO WITH MY MOTHER UNDER CSPA LAW?

Age at time priority dates became current minus pendency of I-130 petition. Make sure beneficiary sought to acquire immigrant visa within a year.

It must be really easy to obtain visitor visas for all countries in the world as a green card holder?

Depends on the country. But subjectively with US LPR (and eventually citizenship) it opens the doors to less restrictions in some other countries...

I dont have any stamp in my passport indicating date leaving US? How will they know how long i stayed once i apply for US citize

Write down the dates. Check your “entry” stamp to the foreign country and then your entry stamp to the US.

Who long does the nvc give appointment for interview for visa i130

Should be within 3 months from NVC filing, unless they issue further requests.

If you get your EAD before expiration then yes.