When installing your ubuntu you are replacing the windows bootloader (partially). It resides in part in the mbr which is where grub can install itself too (partially).
Mounting your windows as /windows isn't a problem
Your recovery partition shouldn't be harmed unless you have marked it for deletion or formatting, same as with your main windows partition.
Btw if you install grub you might as well add a line to start your recovery partition while you're at it.
Btw I'd go with ReiserFS, but that's me