yep
Yes, MPM-Worker in apache2 handles peak traffic a lot more efficiently. However, you will need to run php through mod_fcgid to reak the benefits of MPM-Worker. Trust me it is worth it for the performance boost.
mod_deflate is 62% or so faster than apache 1.3's Last I read. You have access to mod_security that prevents comment spam and other cross site scripting attacks in apache2.
All in all it is worth it.