Q:

Supplies sat in space for five years, are they still usable?

A travelling space fleet found an old militarized asteroid, with weaponry, space suits, munitions, and food which had been sitting there for 5 years. Is it still usable and safe?
Guns- coilguns, powered by a nuclear generator on the interior of the asteroid. Exposed to the vacuum of space.

Did they rust or anything?
They should work if I get the generator back up, right?

Space suits- single unit personal suits that can withstand the vacuum of space. Comparable to the suits that have been used in previous missions(Apollo and stuff). In a pressurized area, but in 0G

Do they still work?
Are they safe?

Munitions- small missiles with an explosive warhead launched from coilguns. Most in pressurized area, some in a vacuum.

Probably need a recharge for the targeting system, right?
Would the ones in vacuum still work?
Will the warhead still work?

Food- Mountain Houses or Ramen. In a pressurized area.

Is it still good?

Generator- large nuclear generator. In a pressurized area.

Will it still work?
Is it safe?(assume it was emptied when the inhabitants left)
How long to start it up?

A:

Parts exposed to vacuum: mechanical parts will have to be recertified and examined for possible vacuum welding. Parts exposed to external vacuum are probably slightly corroded and will require scrubbing and re-passivation.
Plastics and rubbers will as a rule need to be replaced due to storage embrittling (the evaporation of plasticizers from the plastics). Chemical batteries will require replacement. Fuel cell and osmotic membranes (CO2 scrubbers etc.) will also need replacement.
Missiles should work, the targeting system will require recharging but not replacement since it almost certainly uses solid-state supercapacitors.
The nuclear generator is probably good and only needs replacement for parts having undergone secondary activation. Still requires recertification but should be relatively easy to do.
The foodstuff might be a bit stale, but is probably still eatable.

A:

It depends on radiation.
Superfast charged particles aka cosmic rays are bad for biological organisms.  Cosmic rays can also mess with electronics and the effects are cumulative.  Cosmic rays come from various energetic space phenomena but inside a solar system the main source is the solar wind.
Maybe your militarized meteor has all the good stuff deep down inside, using the bulk of the meteor as shielding.  Or maybe it had active magnetic shielding at one time, which has since stopped working.  The cumulative effect of particle radiation on your electronics might have irreparably damaged them.  It does not take much to get fussy electronics to not work.  I might want to put some distance between me and the nuclear coilgun thing the first time you try it.
Cumulative radiation could also embrittle plastic parts of vacuum suits.
Food and water would be best off if it were sterile to start with. Radiation and vacuum is not going to do that stuff any harm.  Ordinary firearms would be ok too if you really have to fight; probably those would do better in desiccated vacuum than they would on earth.  Also if the previous inhabitants had a stack of interesting magazines those will be ok although styles might look dated.

A:

It depends.
It depends on the temperature and position. If the objects are left in sunlight and warm up the result may well be different to objects kept in shade and cool down.
It depends how close the asteroid is to the sun and how quickly it spins. If the items experience a regular heating and cooling cycle it will be more detrimental than if they are kept at a constant (low) temperature inside the asteroid or in perpetually shade.
It depends on the design of the items, items like spacesuits are designed to be exposed to a vacuum and depending on design might well survive quite well. Sterile food should store quite well but again depending on the design of the packaging. Hot/cold cycles might cause containers to rupture.
It depends on the level of micrometeorites in the area. If the items are exposed on the surface this might be significant for some items especially if large areas are exposed there is an increased likelihood of some minor damage.

