IS H1-B visa valid even after you switch your employer??

You are mixing up visa and status. Yes you can use your existing H1B visa stamp to travel but the new employer must file a new H1B petition. Talk...

My finance is a LPR & my visa status is F1. I have got CPT from my school as a result of which I can study as well as work.

Marry ASAP and you should be able to adjust status to LPR within the year. The wait is not 3-4 years.

Travelling to home country for First time F1 stamping (have CoS approval) after receiving EAD/OPT and being employed.

Based on these facts you should be ok.

Family immigration

If he is admitted to the US as A B visitor, he might be able to extend his status for another 6 months. However after that time he will need to...

Hi, My L1B visa is going to expire by Apr 2014. and by that time i am going complete 5 years on L1B. But i-94 is valid till 2015

That doesn't seem right. Get a lawyer to review docs and facts.

Can my fiance enter the US on a visitor/tourist visa while our K1 Visa/I-129F petition is processing?

Yes he can come in if he intends to depart. There is always the chance they will ask questions at the POE and that might lead to complications.

Sounds ok, but I would prefer sending 3 if that's all they asked for also.

I just got married to an american citizen. I lost my i94 and I overstayed a couple of months. Can I fly to NYC?

Either leave the US and apply for an immigrant visa abroad or stay and adjust status in the US. This is assuming you married a USC. It's not a...

Confusion regarding H1B.

An employer needs to file a new H1B petition for your benefit and you would be subject to the cap.

I'm on h4 visa. Can I star my own business and volunteer in it?

No. There is no volunteer for your own company, that's called working.