1:Linux does't bother your other drives, especially if you have another hard drive
2:RH will install GRUB - a boot manager.. so you will be able to choose what OS you want to run
3:Linux is easy to uninstall.. you can format your hard just by doing "rm -rf /"
and all your linux files will be "gone" (actually.. if you want to format your linux partition you can run cfdisk and format the Linux partition into an fat32 one)
Hope that helped