I recently found out about Logical Volume Management. Seems interesting, but I have a couple of questions:
I have had a system become unrecoverable after a power outage using LVM. I couldn't recover a single file from the Redhat install because of the corrupt partition. If it was mission critical I would have found a way possibly, but it wasn't.
If you want to install Windows on an LVM disk, you have to make sure it's compatible with Windows. If you just want Windows to coexist with the LVM area, that should work just fine.
Also, you generally can't access files from an LVM partition unless that particular OS is being run. It seems to be a limitation that will only really affect dual-boot people.
Windows can't read from, and definitely can't boot out of an LVM partition. However, if you put Windows in a normal partition and your Linux in LVM they will happily ignore each other and work just fine (don't forget to put /boot on a normal partition too).
I've had this setup for years without issue. I don't boot Windows often (I think it's been a year since I touched it) but last time I checked it worked fine, and it has never messed up my Linux install at all.
As for whether LVM is safe to use, you should always have backups but I've safely resized LVM volumes several times without issue. If the FS supports it you can even do it online (xfs and jfs do); add a physical volume, grow the LV, and then grow the filesystem while it's still mounted and in use.
It does not matter if you have a Windows partition. Linux will work around it.
It's safe to resize partitions, but you should always take a backup - obviously.
