1. Mouse. I use a Microsoft mouse on my mac. I have never liked Apple mice.
2. Macs can only read Windows NTFS formatted drives. You can try one of the free drivers to try it.
You should be able to copy off the drive to save your data.
You can format it as FAT32 which can be read and written two by both (and Linux if you care!). You did not say the size of your drive, but the issue with FAT is that the larger the drive the more wasted space there will be. There is no issue of data integrity, so the term "dodgy" is inaccurate. Without getting into too technical details, if you have a 500GB drive, you may only get to use 450GB (not actual numbers in either example) and on a 1TB drive you may only get 800GB. There is an advantage formatting FAT on a Mac, it will let you format large drives. On a Windows machine it will not let you format a large drive (I cannot remember the limit). I have done this and switched the drive between my Mac, Linux and Windows machines with no problem.