H1B.Afraid would be laid off pretty soon.

[requirehelp]

Hi,

I am currently working in a major tech company on H1B visa which is valid till 2016.
I am afraid that I might be fired within next two months.

My spouse is also on H1B visa.
I have the following questions:

1. By what time line I should file H1B to H4 Change of status request to avoid being out of status?
2. If I find a company that is ready to sponsor my H1B , then by what timeline my new employer needs to complete the paperwork so that I do not become out of status?
3. Can I start working for my new employer if the paperwork is in a submitted state?
4. What are the documents needed for transfering from H1b to H4?

Please give me some advice as I am in really bad shape.

Thanks in advance for your help.