Having done a lot of long exposure shots with my K110D I'll expand on what I read in this thread.
The simple Pentax Remote device has a button locking feature, I didn't know that initially.
My K110D camera draws over 1/2 amp at 6.5 volts with shutter open. I have killed many alkaline battery sets in 10-15 minutes by holding the shutter open with a cable release. This is why the manual warns against doing a sensor cleaning with weak batteries. At that current you don't get the amp-hours the battery is rated at, plus the K1x0Ds fail when the voltage drops just a little. I can take "dead" batteries from the Pentax and use them in my Fuji for awhile.
To do much astrophotography you need the AC adapter or a big 12v battery and a "not so easy to find" 12 v to 6.5 v supply. Not all supplies will work, I bought a switching supply and found it occasionally caused the shutter to oscillate.
In my observatory I use the Pentax AC adapter for power. For exposure I use a laptop/desktop computer program called DSLRShutter by Stark. I made my own serial to Pentax adapter to use with the software. I doubt it would work on a PDA since it supports only serial and parallel ports. I also made a battery powered timer for remote use without a computer.
Another option is Canon makes an timer around $140 which will function with a Pentax if the connector is changed. DSLR astrophotography is dominated by the "Big Two" so I end up making my own gadgets for my Pentax.
Turning off Noise Reduction will cut the dead time between exposures, but greatly increase the noise. With high duty cycle on a warm night I doubt 10 minute exposures are practical even with NR. I keep NR on taking several 1-4 minute exposures and stack several exposures.