Problems please help!!

[JLHollowX13]

so i recently bought my 92 svx. ive been catching up on maintanance such as tranny flush, oil, p/s fluid, brakes, still need to get a new p/s pressure hose if i can find one somewhere.

my first question is about the tires. when i bought the car it had a bulge in the side wall that i new id have to replace, but then wheni went in to get a new tire the guy said i should get all 4 because its awd and they didnt make that particular tire anymore. he explained to me about how the tires rotate and the gears mesh and all that and he said he would sell me one tire but id have to sign something saying they werent liable for any damage it caused to my car. i decided to think about what i should do and i decided to see what all of you thought because im new to subaru and i could use the help. i dont have the money to get all four tires and the other tires are pretty much brand new as far as i can tell. i wanted to know if it was ok to have different tires as long as the fronts matched and the backs matched or if they all really do need to match. thanks for any help on that.

my second question is about the vehicle speed sensor on the tranny. the speedo doesnt work, well sorta. sometimes it will jump around and ive heard of speedos doing that on cars that use a cable, but since these use a sensor i was wondering if it could be a loose connection. ive never heard of something electrical kind of working, but i may be wrong. ive looked everywhere for the sensor, in manuals, online, and on my car and i cant seem to find it anywhere to see if it is a loose connection. can anyone point me in the right direction or tell me if they think it might be something else? thanks again.

lastly i need to replace a cv boot. is this something i can do myself or would it just be worth it to pay someone? do i need any special tools and what do i need to do to get it fixed? ive got the cv boot already, but i cant seem to find a how to in my chiltons about the boot, all itll say about it is check it regularly for damage... well duh haha. its the driver side outer if anyone needed to know. thanks for any help ahead of time, its very appreciated!

remember im new to this network, thanks!