I've found that my basement studio works fine for long term storage.
We keep the humidity down with an airconditioner in the summer, we don't cool it too much, but just enough to remove the humidity. winter, that room has electric heat. We always run a hepa filter, and dust often. I need my computers just a little below normal room temp all the time.
We keep the equipment in bags as dicussed earlier.
In many years of service I've only had one problem:
My canon pro one (*L series lens with flouride (co-designed by colgate?) lol. Developed fungus in the front lens element and was repaired under warrenty. We can't be sure, but my spouse did at one point drop the lenscap in a snowbank on Newyears eve, and I've suspected but dare not accuse without proof, that she put it away wet.

By the way, when it comes to improv'd equipment, I'd love to hear everyone else's. Liam had one for baby tripods today that looks great.
Of course there'll always be one guy that carries it too far...
I am reminded of a conversation I had once with this biker. I'm into BMW's and Yamaha's Had a K100 at that time. On a Bike trip with tight funds improvising is mandatory, as is camping out. I met this Harley guy...nice fellow an all, but I had to tell him straight.."I don't care how desperate I am for my morning cup-o-coffee, I'd rather eat the grinds, drink some water and sit on my engine block, than drink something you filtered with your old tighty whities...."!

Hi Mac,
Here's my bit on keeping lenses dry, which'll prevent the fungus in the first place. Keep every packet of silica that comes with most electronics you buy ,and dry them out in the microwave or on a radiator. Use 'em in your camera bags. Not everyone can afford top end camera bags or waterproof cases, so here's a tip:
Inexpensive, padded lunch bags and coolers work great, as do diaper bags, (and in my opinion, anybody desparate enough to steal my lunch or diaper bag, can have the camera, we are after all our brothers keepers, and what's insurance for any ways?). 5 gallon pails from a restaurant work great - as cases. you put a cloth bag of rice or beans(doubles as camera support) in the bottom and then a layer of foam padding (cut to a circle doubles as a seat cusion when you are sitting on your pail) and a couple of padded lunch bags with your equipment inside.
They'll float, easy to load into small planes and tight spaces on trucks or boats, atv's etc. people don't think to look into margirne or ice cream pails for cameras....

George saidI prefer to think of it as "Diffusion"
Lovely soft focus schnapps diffusion...

I remember seeing a mirror box with rear projection screen built in that allowed you to place a slide projectoe on one end and a camera/videocamera on the other for dupings slides/transfering to video, might work better...too bad I have no recollection on what brand, or where to find one...

Got a costco in your area?

Hey Mac

Think of it this way- if they can't get the black (K) right, what the heck are they doing to the C and the M and Y? Run don't walk to another photofinisher!!!

Really, some places don't change thier chemistry often enough, check thier water de-ionizers, or buy the calibration negs from the manufacturer on a regular basis and CANNOT COLOUR CALIBRATE thier machines even if they KNEW HOW!
Then there is the skill and care of the machine operator!

Studing your negs on a regular basis- start with the good ones, rember the colors are reversed ( to thier opposites on a color wheel) plus there is an orange mask and you'll eventually learn to see the details and density of a good neg from a bad neg and you'll probably realize that the reason you're "amazed when anything devlopes from what I shoot." is lousy printing on thier part.

I use the ftz500 with my istds2 and had overexposure too. pttl won't work and wireless ttl won't work, but second curtian sync does and ttl does.
one caveat is this- set flash exposure comp in the camera bodies menue to - 1.3 to -1.7.
I remeber that trying the 500 ftz on a dl at the camera store and it went full power..no damage to the flash or body but ftz compatibility is one more feature stripped down from the ds to the dl.
maybe selling the ftz will ofset the cost of the new flash for you.

ps my preferred method of using a two light setup like that would be to put the smaller manual unit on camera with a tissue and rubberband for a diffuser and the vivitar bouned off the white cieling, my camera set to match the thyristor setting on the vivitar.

Hi Mac.
If your two lights are not aimed in such a way as to cause the light from your small light to hit the sensor on your vivitar, (ie- 45 degree angles on iether side of camera, ) then the vivitar will cut out at the fstop indicated on the scale. It will in fact read the light reflecting back to it. The combined light of both units. Therefore you must check the guide numbers of the smaller unit and ensure it is at least one stop less than the thyristors setting. You can control contrast by moving the smaller light closer or farther from your subject, ( or taping paper or difuser to unit) and underexposure should not happen, however it would be easy to overexpose if the flash output of the smaller unit is higher than the vivitars setting.