Immigration: I-131 filing with I-130/I-485: is 30 days 'expected length of trip' reasonable?

Yes.

H-1B to B2, now want to change of status from B2 to H4

I don't foresee any issues with changing status to H-4.

L1B Visa holder will be laid off by employer. Can he find a job from another company?

Job hunting should not be a problem. However with exhaustion of H-1B numbers for the fiscal year, you may have to wait until April 2014 for your...

Usually a conviction has consequences. If you were not convicted and charges dropped, there should not be issues with submitting the paperwork. ...

Extend the B1/B2 visa for 9 more months

I do not recommend seeking a 9-month B-2 extension based on these facts.

Can a conditional green card holder travel outside the country for a few months?

You can make a temporary trip abroad.

Can H-4 visa holder work outside the US?

As far as U.S. is concerned, one cannot work if he/ she enters in H-4 status

Changing employer

If the I-140 approved is revoked after the extended review, you can retain the priority date.

What documents should be submitted for change of status from B2 to H4?

It will be best to work with an attorney as he/ she will review when the person entered the U.S., when visa was sought, etc. to determine if there...

Change from B2 to H4

Yes, you seem eligible to apply