Alarm sounds and car wont start on my 1995 subaru

sounds like your linkage may have disengaged and the trans is stuck in neutral. You need to get under car and check trans linkage.

If your just dealing with the alarm/horn going off all the time, you can try disarming it when it goes off by putting the key in the ignition and turning it on and of three times ending with the last turn in the on position. This will stop the alarm from sounding.

Subaru Keyless Entry Security Alarm Immobilizer Key Remote Start... go to that site and scroll down it has detailed instructions on the factory alarm systems

I've changed quite a few ignition switches on Subaru's after 150,000 miles. It could also be a bad connection at the starter (the small wire) or a bad starter.

From what you have saud it sounds like the timing belt has lost a few teeth. In other words it is out of time.

check exhaust for blockage(cat) might be bad.

coolant senor

you HAVE to get a remote and unlock the car.the dealer may be able to turn it off with the obd2 system,you have to call subaru.

cycle the ignition key on and off 3 times

if by a/t you mean automatic transmission try a power purge transmission service it may have a filter sensor that is telling you to service soon