The OE front speakers are 6 1/2"
1. Yes you will need spacers. You can make it out of 3/4" MDF, plywood, or any other dense wood. Or you can get the spacers from a 96-99 Outback, they will work too. djrez4 wrote a great front speaker install here OK...full front speaker install with pics!
I'm not sure if 5 1/4" will fit in the rear locations.
2. All the spare tire enclosures I've seen have been custom made. You can make one yourself, or have an audio shop do it. Do a search in this forum and check out this thread http://forums.nasioc.com/forums/show...guy+spare+tire