Yes, you can keep FrostWire if you want to...it's pretty much the same as LW & connects to the same network

Before you uninstall LW, just check where your downloads are saved. Tools > options > saving will show you where they're stored. Then you can move files into the FW saved folder if you need/want to.
I haven't used FW for ages, so I'm not sure if the saving locations are the same for both apps...it used to be the same but that might've changed.