You can just compile normal Wine for OSX (search on google or this website about it). Crossover is not needed. From personal experience with porting apps using Wine to Linux and OSX I can say that the default OSX X11 server is broken like hell though. It has nasty bugs, it doesn't integrate as well as the Crossover X11 server (e.g. no command+tab because X11 windows are not accessible that way) and other bugs. For the second question look for winelib which allows you to mix win32 and linux/osx code but you need to compile ALL of your code using winelib. You can't just link to Wine as if it were a library because we have to perform a lot of 'magic'.
