Legally speaking you can't and shouldn't install LED bulbs because the existing assembly will NOT aim the LED bulbs in the correct direction. The Reflectors inside the assembly were designed only for Halogen bulbs.

Heated mirrors you state were stripped by the dealer. Can you elaborate on what they did? Did they remove the button or factory mirrors and slapped on non-heated mirrors? If that's the case, nothing stops you from going to the wreckers to find heated mirrors. That's what I had to do with my 2001, when someone smashed one of the 2 mirrors on it. Found a heated mirror, repainted and reinstalled. My 2001 came with the heated mirror option.

Heated windshield, I am assuming you're talking about the bottom heating element where the wiper blades sit. To fix that you'll need to get a new windshield installed with the heating element. Again, this is assuming you actually have the button.

 

If you just want to replace the bulb, Don't! Here's why:
1. Street Use of LED Bulbs
2. Why Most LED Headlight Upgrades Don't Really Work: An Expert Explains - Jalopnik

 

I recommend you add auxiliary LED lighting rather than trying to make them work in the headlight assemblies. I don't know if there are complete LED assemblies but I'll bet they cost much dinero.

 

Personally with this series of Forester you have 2 solid options for headlight upgrades.
1. Purchase the Factory HID setup. They are direct plug and play, although you won't have the leveling system. 84001SC200 and 84001SC210. They are NOT CHEAP/
2. Install H9's in the lows and gain almost 1000 lumens. Light source, filament orientation is identical so for the most part the reflector housing will handle that. You can also buy a set of Philips Automotive Lighting 9011 HIR for the highs, and the mod takes about 15 seconds per bulb to fit like the H9s.

I ran option 2 in our 2012 for probably 6yrs+ until the plastic finally fogged over so bad. Then I went to the factory HIDs.

 

slvrwrx02. I sold a Mitsubishi a few years ago and one of my heading feature drawcards was I stated "Glass" headlight lens!

 

Read closely what your State Regulations say about lighting. You might not be fixed to only two low beam lights. Our Australian regulations are mostly direct copies of the European standards. From distant memory, as I remember the number of lights are fixed to six or eight and the number of low beam lights are not fixed to two. It is all about beam spread and glare for oncoming drivers. I remember seeing a car with four low beam lights.