Working after 240 days in H1B Extension + Amendment type

[Working after 240 days in H1B Extension + Amendment type]

I am on H1B visa and my extension petition is pending with USCIS. I am presently on 240 days period, and it is going to end in another 10 days.  My employer says I can work even after 240 days since my H1B extension is filled as “Extension + amendment”.

 

Can any one confirm on it?

[upgrading applcation to EB1 from Eb2]

If a Green card application is filled under EB2 category, can be changed to EB1 in future?

[switching employer]

I am from India and got H1B from my employer and the  H1B visa is going to expire by Oct'15. Unfortunately I did not get any single opportunity from my employer to travel USA hence I did not travelled a single time on H1B. So Can I look out for any other employer to travel to USA, if I make any such moves then present employer harm my H1B like revoking, etc?