You can use NTFS, with ntfs-3g on the Linux side. I've done that and it worked smoothly, if rather slowly. FAT is just too 90s for serious use.

You'll likely want to continue using a native Linux fs for whatever you don't need to share.

Dunno about quality of any Ext drivers for Windows.

As for partitioning, back in my day people just slapped another primary partition. It's not like Windows supports Linux LVM.