Actually, Winchester does still carry their Super-X 55grPSP loading of the .225. Catalog number is X2251.
It had been dropped for a year or so, but it is still available as one of their limited production annual runs. These do sell out pretty fast at the major shops, some of the less shopped places online still show some in stock...but they are usually priced quite a bit higher than the bigger places like ableammo, midway, grafs, etc too.
Winchester also has new .225 brass available for reloaders yet and dies are available from pretty much all of the big brandnames.
I suspect they brought it back from the dead due to customer demand. I know several guys up here in ND that howled when they discontinued the regular production runs back in the early 2000s.
There are still quite a few .225s out there and the .225 is also the base cartridge for a few wildcats so I think we'll see it available for a while yet...even if only in those low-production seasonal runs.
Good reason to stock up on ammo and brass anyways.
As for the 340 itself,
Check here for a parts list and diagram... http://www.wisnersinc.com/rifles/savage/325-340.html
I don't know if I've ever seen a link for an online manual for it. It wouldn't hurt to contact Savage to see if they still have one available but I doubt it. As boomer said, probably your best bet would be to watch the auction sites or see if someone that has one can scan theirs for ya. I would if I had one...all I've got is one old 340 in .222 but no manual either.
That cheap little Savage is a good rifle! The .225 is an excellent little cartridge too...it just got overshadowed by the .22-250 (and the .220Swift that it was intended to replace).