Waited over 10 years. Immigration Interview. Kids now Over 21. Options?

It does not matter that the fees were paid. The children have possibly aged out if not protected by the Child Status Protection Act. (CSPA).

Can dependent work during L1 extension period ?

No, the dependent must have a valid EAD card.

When do Temporary guardianship expire?

It appears that it expires in 2014, assuming the child has not yet graduated college.

Could I travel back home to Israel while my H1B (Working Visa) is being processed?

You would be abandoning any requested change of status, however, you may be able to obtain an H-1B visa while overseas i the petition is approved...

Form N-400 Part 9, question 9 (my marital history): Do i complete this section if divorced and obtained GC through employment?

Yes, you must complete all sections of the N-400 unless explicitly not applicable.

Citizenship interview

The applicant must be residing in marital unity with the US citizen spouse to be eligible under this section of law.

F-1 student filing for Green Card

That appears to be a complete list of the forms, but there is much more involved than the forms.

I would like to get my sister from another country to Oklahoma USA

There probably is not another way for her to come here, but you should consul with an immigration attorney to make sure you discuss any potential...

Pending adjustment status when can I apply for SS# for my wife?

She can apply for a Social Security number once she received her work permit.

Assuming you are authorized to work, opening an IRA should not be a problem. You may want to consult a CPA or Financial planner.