Travel to India on L1B when H1 RFE in progress.

I am on valid L1B visa which is valid till March-2015.

Applied for H1B-2014 & its picked up in lottery, RFE received & response submitted on 8-Oct.

Now I am planning to visit India for a month on L1B so my questions are –

If H1B gets approved during India vacation,

Will my L1B still valid?

Can I travel back to USA in L1B?

After going back to USA will I be able to work with my old employer with L1B visa or would have to change job with H1B?

Do I need to apply for Change Of Status (COS) to make H1B legal to work? How long will it take and $?

Thanks