Last year feb 2012 I have stayed in US for 16days after my L1 B extn denied. now i am applying for L1 A. is there any problem??

You should not have trouble explaining to the Officer the reasonableness of exiting after 16 days.

What if u have an unconditional green card from your marriage to a us citizen?

No requirement to notify USCIS. Be prepared to be interrogated about bona fides of marriage based on which you obtained residency down the line...

Can i file H1B this year even if my current L1B visa expires in June 2013 with I-9 Expiry on June 2015

Yes, though you are confusing the visa validity (which is for travel) to your status (which is determined by the I-94.)

Is a 1983 Green card still valid?

As long as there are no issues with inadmissibility or removalability, he can seek a replacement card and travel.

No. The only way you can proceed after entering is to marry your USC sponsoring fiance within 90 days and apply to adjust status. If you decide...

Would i have to leave the u.s?

Provide more information regarding how you entered the U.S. and when.

My husband and I are asked for a second interview, the first one she asked questions only about his first marriage

You should request representation or at least one personal meeting with a competent immigration attorney to discuss factors which are going against...

Am I eligible to change employers while on EAD when my I-485 had been pending processing more than 180 days?

Yes. It is advisable that the new company provide a portability letter to support your pending adjustment application.

Can I travel ? I am new to USA and have 10 year Green.

Assuming that nothing conspired making you inadmissible, keep the trip short to maintain your residency. If you will be away for long, you may...

I 130 and 485

You can always file an incomplete application. However it will result in a delay in processing as you will get a request for evidence (RFE)...