Traveled outside while COS was pending and H1B petition has been denied?

That is all correct. you must go home to the US consulate to get an H-1 visa in order to acquire H-1 status. I can't believe your attorney/employer...

Travel during COS(Change of Status) is pending

The change of status would be abandoned. Doesn’t your attorney know this?

Will there be a NIW withdrawal receipt?

If the withdrawal was sent by Fed Ex or Express Mail, you will have proof it was received and that is all that is necessary. Why was the NIW...

Is it allowed to work on two different visas simultaneously?

You cannot work in H-1 status and O-1 status at the same time. You can work for two different H-1 employes as long as both H-1 petitions and LCAs...

Do I need to inform USCIS that my father naturalized after I filed for I-485 in F2B category?

When your father naturalized, that automatically moved you from FB-2B to FB-1. You may want to look at the quota for FB-1 again.

H1b to f2 when visa stamping is denied and I140 approved?

With an I-140 approved your F-2 visa will almost certainly be refused. Why wasn’t your status changed along with your husband’s?

What Visa should I choose? My F1 got rejected twice and also my B1/B2 was revoked w/o prejudice.Wife working on F1 OPT.

Unfortunately, there is no visa for you in this situation. Your wife needs to change status to H-1 whenever possible depending on her employment,...

Travel abroad after my interview and before my oath ceremony ?

You are not a US citizen until sworn in. You are still a permanent resident until then and can, therefore, travel whenever you wish.

When can I expect my interview ? why its taking too long?

It is taking "too long" because CIS is very slow.

Yes, it is possible the CPS case may impact her immigration options. But what really matters is understanding exactly what she is waiting on and...