Sometimes, it is useful to the Engineer to know what type of "sound" you like or don't like, you can tell what you like as artists, cd's etc. This will certainly help to get what you expect (if you expect anything else besides the pacing and homogeneity).
No, compression is fine, if you like how it sounds with it....same for reverb.
Disc verification or DDP Master creation is a standard process, some may charge a flat rate or per hour. I guess if you wish to get MP3's, you have to pay.
Your best bet is to call your ME and ask him these questions, I am sure he will explain in details what you would like to know.