L1 to H4 (COS) to same L1

[zenbud]

L1 --> H4 (COS) --> L1. Have only L1 stamping in passport.

I got myself into a confused situation. I entered on L1 on Nov 2007 and was on L1 until Aug 2008. I applied COS to H4 (as I was pregnant and couldnt continue working) in Aug 2008, and currently im on H4. I dont have H4 stamping on my passport. The L1 stamping on my passport is valid until Nov 2009. Now I have recovered from my post maternity period, my employer has asked me to join as soon as possible using the L1 which I have.

Question:
1. Does COS from L1->H4 invalidates the L1 stamp on my passport?
2. Is it possible for me to travel outside (to canada or mexico) and get new I-94 card at the port of entry using my L1 (which will change my status to L1) or do i need to get another L1 stamping.
3. if its possible to get new I-94 at a border post, is there any risk involved?

Any info will be helpful.

Thanks.

 

[zenbud]

Additional Question

Also:
* If the Officer at the POE doesnt let me use my L1B, is it possible to enter back in H4 status (I have the H4 petition approval with valid I-94) without a stamping (if I do re-enter within 30 days)?

Any info will be really appreciated.

Thanks.