MIgrating from local to host and back

I have several commercial sites using wordpress. I’ve created several local projects within my local install of wampserver so I can work on them locally. Each folder in the www directory has it’s own name and it’s own wordpress installation. My problem is with migration between production and local.

Each local wordpress install has the usual tables within it’s database with different table prefixes for each database. All of the production sites have the same database structure with the default wp_ prefix.

My question is…

How can I export/import while keeping my same username and password on the local machine (which is the same for all the installations), while keeping the unique username and passwords on the production sites? Do I just export/import everything except the wp-user table?

Also, how do I handle the unique table prefixes on my local machine? Do I need to change the production sites so that the table prefix matches what I have on my local machine to be able to import/export? I suppose I can change the table prefixes on the production sites but I’d prefer not to. Has anyone else dealt with this? I’ve been a professional coder for over 25 years but I’m fairly new to wordpress. It’s a neat tool for rapid development so I’m anxious to learn.