if you want to run VST plugins, there should be no problem doing so if you have installed wineasio (wich is described in another thread and in the tips section).
It should be something else when you try to run standalone plugins (meaning binarys: *.exe)
To the Mac/windows issue: Like i said above, if they are VST plugins (which most of them are on both win and mac) there should be no problem. U only have to copy the plugin (.dll file and maybe banks etc) into the folder you set up in FL for plugins.
Then, when you want to insert them, do as usual, but instead of searching for them in the list, go to "more". Once there press refresh (or was it scan, i dont remember). It should then show up in the list. Just put a "F" in the check box next to it and it should be available as you are used to in the list with the other instruments/effects..
Hope this has helped.