The rear LSD wasn't added to the Legacy until the '00 model year. I don't even think it was an option before that. I'm not sure about the Legacy Outback - does anyone know if it had a rear LSD before the rest of the Legacy line?
As for the torque split, it depends on the transmission - is yours an automatic or 5 speed? The automatics have the 90/10 split using a computer-controlled center diff. I've seen a great deal of debate about how far the center diff can transfer power in the automatic - some say only 50/50, others say it can go all the way to 10/90. The 5 speed uses a viscous coupling center diff, so it's a 50/50 split by default and I think can go all the way to 100/0 or 0/100, but I'm not sure.
Regardless of what transmission you have you can put in a LSD rear diff from a newer car. I've never done enough research to figure out if the axles will bolt right up or if you'll need other parts to make everything work right.
The weak rear defrost seems pretty common. On some days mine seems like it's on fire, other days it takes forever. My office-mate has a brand new '02 Outback H6 sedan and he has the same complaint about his rear defrost.
'97 Legacy 2.5GT sedan