Re: @AC "7 mins"" (whatever that means, ElReg) Americans, Indians and Europeans....
"One, and I haven't done the maths, I'd imagine you'd have to start doing some orbital corrections if you fired one of those for any length of time"
The 23mm Rikhter fired 0.168kg shells at 850m/s (no idea of propellant gas mass), and the gun had 32 rounds. At launch, the station was 18,900kg; I don't know how much mass was lost due to maneuvering and life support requirements. The guns were only fired near the end of the station's life.
By conservation of momentum, 32 x 0.168kg shells at 850m/s would recoil the 18,900kg station at 0.24m/s. That's not a major course correction, but something to be noted in the long run.
"Two, if they did test fire the one on the Almaz, where did they point it?"
Well, the Salyuts ran in low orbits - about 210km in the case of Salyut-3 - so orbital life times were short. If the guns were fired against the orbit direction (or within the 180-degree stern arc), then the shells would have even shorter lifetimes. If fired within 75 degrees of either side of dead astern (i.e., over a 150-degree rear arc) then the 220 to 850m/s reduction in the shells' orbital velocities means they'd hit atmosphere pretty soon - minutes, at a guess. Even firing within 76 to 87 degrees of dead astern imparts a large de-orbit kick of 45 to 205m/s, which is as stiff as any spacecraft's intentional de-orbit burn. (The velocity imparted to the shells perpendicularly - up, down, left, or right - to the station's orbital track is less relevant for determining orbital life times.)
"or they fired it at the planet which might be an act of war?"
Whatever bits of the shells survived re-entry wouldn't be much of a threat. The explosives would've cooked off and the shrapnel would be falling at a modest terminal velocity. Considering Canada didn't go Rambo on Russia for spraying radioactive satellite fuel over it, I don't think anyone was going to declare war over some scorched, small bits of metal.
"Either there is a nasty burst of 32 slugs in orbit waiting for some poor sod to wander into their line of fire - which is rather irresponsible"
Firing forward gets trickier, but I can make one general statement about any Salyut shells fired ahead of the station: they're always going to return to their point of origin, which is a low perigee of 210km. An 850m/s boost straight forward would extend the shells' orbital lives by putting them into an elliptical orbital with an apogee of several thousand kilometers (I think), but their perigee is going to remain c210km since they have no motors to alter the perigee. Assuming they didn't actually hit the station at some point, the shells' low perigee would mean they'd re-enter pretty soon, under a few years, though they'd be in orbit longer than the station.
Of course, the risk of the shells hitting the station - which was doing useful work even while unmanned - is a good basis to assume the gun was only fired backwards.