Seeking advice on following situation

My employer is terminating my job on 2/15. I'm on H1B, valid through 8/02 and renewable through 4/03 (provided there's no job interruption).
An LCA was filed with Labor Dept using current job description to support a green card application.

I'm currently looking for a job.

If don't have an offer by 2/15, should I notify INS/Labor Dept asap and change to a tourist visa so I don't burn up the remaining validity of my H1?
Or should I apply for an Employment Authorization Doc? What are pros/cons between being under a B type or an EAD while looking for a job?
Being subject to same taxes as a US citizen/resident, I assume I am eligible for unemployment benefits: how does this work?
I read about Unemployment Insurance paid by employers: how does this work?

If I accept a job with a new employer and a petition has been filed with INS, will this impact the validity of my H1? For ex, if I have a job I can start on 4/15, when should I renew my H1 (expires in 8/02) and can it be extended to 6/03 instead of 4/03?

Finally, would accepting a job with a different job description than the one used to file an LCA affect the green card application?

Thank you for your input

Fred