There are a few things that are unclear to me regarding libraries and compiling.

As far as I know, there are 2 options when compling own project (with third party libraries).

You can build libraries with own compiler (to save compilation time), or you can include files in your project so that compiler builds them each time you want to build your project.

Lets say I build static libraries using MSVC 8 (2005). I want to use them in my project. Should I rebuild static libraries if I change my projects settings (things like debug/release mode or any other things)?

In other words, can it happen that my project will be built in release mode, and static libraries that are being used will be in debug mode in this case?

For instance, some time ago I had to build iostreams zlib library. Does it make any difference if I use this boost library and I build my project with different settings?