I am not aware of Win7 can be booted by a floppy but Xp can do that.
As far as Grub is concerned both Grub1 and Grub2 can be accommodated inside a floppy!
Grub can be placed in any partition. It only needs access to the boot sector of that partition.
I put my personal data in a data-only partition so that it is accessible to to operating systems. Grub can be placed inside. However it is wise to put as many boot loaders in a partition for just the boot loaders as they are supposed to be able to co-exist with each other!
I certainly have the boot loader for Dos, NTLDR (that boots Win2k and Xp), bootmgr (that boots Vista and Win7) and Grub sitting side my side in a Dos partition for booting the 50+ operating system in one hard disk in one of the box. It is easier to maintain.
Grub2 can read a NTFS partition so one can house Grub2 inside any MS Windows to boot Windows as well as Linux. This is achievable using the standard "grub-instal" command in Linux that has Grub2.
There are many tutorials for using Win7's bootmgr to boot Linux. The key steps are included in the Just booting tips of my signature but a more detailed write up is here
I have tried using bootmgr to boot 150 Linux before by write a batch file (script in Linux). I would say Grub is between 2/3 to 1/2 less work.
bootmgr only chainloads a Linux.
As a rule any boot loader can chainload an operating system as long as that system has a boot loader residing inside its partition. In chain loading you just use one boot loader to boot another boot loader. It is always the second boot loader that fires up its own master. That is nothing to it.