Should I provide a letter of "future employment intent" from my previous employer when my current employer files for I-485 ?

Time to hire an attorney to sort through this. The facts you have provided are a bit muddled.

My husband can get f-2 visa as a dependent of me? I am an MBA student in USA he is government employee in India since 2014.

It's certainly possible. You will have to be diligent in preparing your forms to submit for his application.

Travelling from NYC to Toronto by bus with a green card only

It would be better if you had a valid passport from your native country. A green card just permits you the right to live in the US and does not...

RAISE Act - People who already have an I-140 approved and are waiting for the priority dates to become current?

The RAISE act is only a proposed law. It will be a long time before any new legislation is passed. With the Senate as divided as it is today, it...

Overstayed my TN visa by 60 days as a Canadian citizen in the US? What consequences will there be from this?

it could present an issue, yes. Be sure to run this by an attorney.

Can I travel(first time) to US from India with amendment receipt notice. ?

This is a question best answered by your employer's counsel. They are in the best position to advise you in this situation.

Can I work while my OPT is still active and I have submitted a change of status after having married an American Citizen?

Yes, you will be fine. If you get married now, you will have more than enough to get your work authorization pursuant to your green card...

Should We be worried?

You could have sent in the advance parole document with your !-130 package. Once the application is being processed it's not advisable to leave...

Seems possible he is on the radar for deportation. Has an ICE detainer been placed on him?

Under which category I can file I-765 with I-130?

Since your parents live overseas, you need to file the I-130 first. They will be processed at the consular level.