Obviously until the RFE is received you cannot respond. This stuff is hard enough without chasing shadows. Looks like your attorney is on top of it.

Should I hire an immigration attorney?

If by legal memo you mean an appeal or motion to reopen you are advised to hire an immigration attorney. But you do not say where you are in the...

What is canclled without predjuice ??

Typically used when there is a mistake or duplicate. Does not affect other visas.

Can we proceed with K3 visa?

Do not expect to use the K3 now that the I130 is approved.

Recently i got visa to travel to USA to visit,with R B1/B2 multiple entry on reaching port of entry i was denied

If you got a denial you obviously did not meet the necessary requirements. Schedule a visit with an immigration attorney.

L1 RFE

There is no way to tell if the RFE signals a problem or not because you do not say what it is for. However, it is highly recommended that the...

Your case is the type that is better suited to review and guidance by an attorney. Approval of an I130 can itself prove problematic and you can...

3 week after interview was canceled no any update

There are so many possible reasons for this that to try and answer would be foolish. But 30-60 days not out of the question.

My friend has a son (age 4) with downs. Can he apply for a work permit ? (No lawful status)

There are no work permit programs for dads with sick children.

The question that has to be answered is the breath of your experience. Based on your facts an RFE is probably in the making.