How to uninstall Logic Studio ?

You can't install the application on an external drive, as the application has to be on your system drive - the same for it's support files and frameworks.

You can put some of the content on external drives, but not all of it. There are a gabillion threads on installing content to external drives, so use the search function and it will give you all the info you need.

You need to delete the application, delete the Application Support/Logic folder, delete the installed jam pack loops and instrument content (which get installed to your GB libary AppSupport/Garageband), then you also need to check the AppSupport/Audio folders for things like impulses and preset settings.

Check both system and user app support trees - by default, Logic will install preset content into the system areas.

This will get rid of the core stuff - if you really want a full list, you need to go into your package receipts, as there are a lot of other support frameworks and packages that also get installed by default (Applications like Soundtrack Pro, Mainstage, support apps like the loop utility, Compressor, and all kinds of video frameworks, Quicktime and other stuff).

There isn't a quick "uninstall" option.

So I really don't recommend a "clean" uninstall at all, just remove the content.

What version of Windows do you recommend, if you want to use Windows
apps on your mac ? (XP ? Vista ?)

Why are you asking me? I can't stand Windows, and have no idea of what windows applications you want to run.