Can my husband & I go to Torronto from USA and get our first time H1B and H4 stamping done at the same time?

You do not qualify to apply for new category visas in Toronto if you are not Canadian citizens.

I am an LPR. I married my wife this year. She has two daughters (10 and 14 years old) do i have to file I-130s for all of them ?

If currently physically present in the USA best to file an I-130 for each.

How can i get entry to just visit USA which i got deny on niagara border(On road)...I am canadian citizen?

Based on your fact rendition you are inadmissible to the USA for previous overstay of more than a year.

Do i have to pay renewal fee for i765 form?

No - the I-765 renewal/extension is free. Fee for it already paid with that I-485.

I have attended public high school in the U.S. on F-1 visa after 1996 and I have not reimbursed my school. What would happen?

This is not something one wants to admit to in a public forum. Contact an attorney privately and confidentially.

H1b status dilemma

You could always claim your "60 day grace period."

Can my wife continue working for her current Swedish company remotely in USA?

Can only (legally) work in the USA once in possession of an EAD.

Can we go together for the interview or should I wait for my H1B Visa stamping to get done and then do for her separately later.

I agree. Your wife's "denial history" could become contagious. Apply alone first.

My H1b is expiring in a year. No GC has been filed. My employer wont file GC. What options do I have to continue working in US?

If cannot quickly find another H-1B employer willing to sponsor you - immediately - you will have no other option but to temporarily enter H-4 status.

Experienced attorneys all have copies of such letters used in past cases for the most part.