The voltage & polarity is usually printed on the appliance next to the power socket.

Make sure you give it enough current capacity, cameras are high drain appliances, the K100d model needs 3.5A IIRC. Most consumer PSUs are under 1A.
I ended up getting a 7A selectable voltage switched mode one, for the K100 (~£20). The Pentax model is reportedly 6.5V 3.5A, but 6V works perfectly (Its about what the 4 AA batteries give).

I've had software occasionally decide to delete the EXIF data by itself.
Fortunatly one of my (free) image editing packages allows the file to be saved with the EXIF from another image so I could restore it from the unedited original. {EDIT: Just checked it's FlexPhotoDB}

You can probably remove it by saving as a different file type (BMP??)- I'm sure there are many that don't support EXIF.

No doubt there are also packages allowing you to edit the data as if it were a text file, and put in what ever you want...

Due to the smaller sensor the field of view of your old lenses will be less than your used to - DSLR view is equivalent to a lens 1.5* the focal length. As the lenses more than fill the sensor.
Old M42 lenses etc can also be used with an adapter...

All this is true for all Pentax DSLRs (except the medium format 645D), so the model you chose will depend on the features you want & the depth of your pockets, though even the most expensive model is reasonable compared to CaNikon

One of the older computers I've used at work was purchased in 1979 for ~£32,000 (An HP 2113b mini computer with specialist software/interfaces) - it came with 32k of 'magic memory' but unfortunaly had no disc drives.
Booting it involved feeding a series of binary numbers directly into the registers, to get it to read the special tape drives.
Thankfully we got rid of it 15 years ago.

My first home PC (1989?) was ~£1000 for a 40MHz 286 - I didn't think I could stretch to one of the new fangled 386 machines and it was a step up from the BBC-B with IBM coprocessor...

At the ultra wide end focal length is not much of a guide on angle of view (what you get in the image!)
The Pentax 10-17 gives a much wider AOV than the Sigma 10-20 when both are at 10mm. From what I've heard the Pentax & Sigma are complimentary despite the apparently overlapped ranges.

Unless I can get a copy of the sigma for under half price there's little chance of me investigating this for myself though. (Sorry no experience of the Tamron either)

There must be a simple way around this - most of my e-bay purchases from China are post free, even in one case for goods costing only 24p! (An USB SDHC reader that arrived & works well)

Higher value purchases will attract Customs duty - A minimum of 20% VAT + the couriers handling charge (typically £8 )

Desiccants reduce the amount of water that's dissolved in the air, and start to have an effect fairly rapidly, even if they don't reach equilibrium for hours.
Warm air certainly holds more moisture, but if you can dry the air whilst warm you don't get it thrown out of solution (condensing as droplets) when it's cooled.

I tend to keep a number of reusable desicant cartridges in my camera bag. Ideally the optics should be in a air tight container with the desicant.

If the silica gel bags have been in the general atmosphere for some time they may have little effect (they do get saturated).
Silica gel can be dried in an oven at >100°C, but the normal bags get unstuck (A vacuum oven set at 70 works OK but I doubt you have one). Molecular sieve (& I think Calcium carbonate) absorb more water than silica, but are more difficult to dry - and I suppose not so generally available.

Weather sealing should reduce the prioblems with condensation considerably, but if you've got moist air inside the seals it could still be a problem, with extreme temperature shifts.

If there's a chance of a lot of salt spray I think it's worth adding a filter, but otherwise I wouldn't bother.

Thanks for the reminder - it's high time I recharged my desicant - this time I'll add an indicator card as well

Sound to me as if the story about it being your grandad's might have been because he couldn't afford it either! If my wife find out how much I've spent on photography, it could make it expensive in other ways...

I've know of a case where a friend specifically took a day of work to be in for a Parcelforce delivery. The driver dropped a card through the door to say no-one was in - without ringing the doorbell! Apparently this was witnessed by a neighbor across the road. My friend eventutally had to drive to the nearest depot to collect his parcel 24 hours later. To make matters worse the depot is in the same town the parcel was originally sent from!

I've had RM send a book back to the US because I 'didn't collect it'. Unfortunately they never bothered to leave a card (so I couldn't have collected it) Sometimes international parcels take weeks (I've had a book take over 5 weeks from the states & parcels from China arrive 2 months after posting), this one arrived to the local sorting depot in a couple of days, and was sent back 28 days later.

Although I've had couriers deliver ripped boxes (once with parts missing that turned up next day) I've never had them fail to deliver. I wish I could say the same for RM.