Problem with defining my objects in installation project

Hello you all.
I'm compiling an installation project for another project I have which was converted from VB6 and therfore includes VB6 componants (I'll explain this detail ahead). When I first made an installation project it worked perfectly but when I uninstalled it deleted the source file of my VB6 componants and thus destroyed VB6 functionality as well as my projects'. Then I figured I can mark those files with permanent only then it keeps the file forever and as it changed the registration of those files, my VB6 now refers to the file in my not-so-long-ago-uninstalled project (Like saying MSComm is in that directory). So to simplfy it here are my two problems.
a. How can I make sure uninstallation won't erase critical files but will delete them if they have another reference?
b. How can I have my old VB not change its references to those of the new application?

and a bonus:
c. How can I make sure my installation verfies Framework is installed and if not - installs it?

THANKS!