US parent with Canadian children.... Which to pursue.....citizenship , naturalization or landed status

No, they don't. The Child Status Protection Act of 2002 says that the US parents must reside in US 2 years after age 14 before US parent is...

I am on an H1B visa and i wanted to switch job so i got my H1B transferred to another company but i never joined them.

No sure if any conflict, but you need to consult with company lawyer.

Immigration Bond

Be sure to involve the Guarantee, the person who posted the bond. He can contact ICE and ask for the bond money.

Immigration

TPS is not a status and has nothing to do here. The priority date must be current.

Form I - 864 Affidavit of support for my Green Card.

Looks like you are eligible to adjust status if no inadmissibility. Your wife has to file I-864 as well as your co sponsor.

Removing conditional green card

Perhabs that is all you have to do. To be sure contact an immigration lawyer.

Getting married and applying for a GC during the grace period of J1 visa

There is no problem so ling as you get married to a US citizen and file immediately. Do you have any criminal records?

You have your answer ECFMG is way to go..Good luck.

Travel outside during I-751 processing

Travel abroad should be fine. Be sure to take all your documents with you including your old green card, passport, divorce and extension letter.

Does Federal Subsidized Student Loan from FAFSA have impact on pending 485 application?

If she did not hide her status and was truthful on all applications filed for FAFSA, then no there is no problem.