As far as i know Veritas can't recover Retrospect data.
To transfer the files across you can either network the two machines together or buy an external hard drive, format it FAT32 and drag and drop the files onto it from the Mac then attach it to the PC.
If you've got files larger than 4GB FAT32 wont work (i think?) So networking is the method for that.
As for file names, i can't remember the length limitations, just make sure they don't have any odd characters and you should be fine.
As copy in batches rather than all in one hit, that way if it glitches you wont have to start from the beginning to be sure that it's all perfect.