1) Flash Lite is not ubiquitous like Java is. Flash Lite for gaming is probably best suited for Symbian s60, the new FL 3.1 distributable player for windows (public beta in some countries), and Verizon BREW. You also have Sony Ericsson project capuchin phones which have a standalone and packaging format for Flash Lite, though this is still fairly new to market. The final platform to consider is Nokia series 40, however only Nokia series 40 5th edition phones and greater have sufficient packaging to use for game distribution. Things will get better for gaming as the distributable player option becomes available for more smart phone platforms, like Android.

2) The interface can be much different between a keypress based device vs. mouse event PC game. Also there are performance issues and version issues. I doubt you will be able to simply save a PC game as Flash Lite and have a satisfactory experience. The amount of porting will depend upon screen size and performance issues.