There are a number of calibration devices on the market, however I would suggest that The Spyder and the X-Rite i-One are the most popular. I've not used the current Spyder's as I have the X-Rite, which I can say works well on both PC and Mac.
If you are going to Focus I'd wait until then to make a decision as you could visit the Colour Confidence stand and view both models. Plus there may be show offers available,
As far as the number of PC's / laptops you can calibrate, you need to check the End User licence Agreement. I suspect you get what is known as a site licence. This means you can calibrate as many machines as you like provided you own them. How this is policed in practice is anyone's guess!!
As far as to frequency, the usual period is monthly. Most calibration software has a small utility that pops up and reminds you to calibrate. ( Usually just when you don't want it to).
As far as the printer is concerned, well you need to use software that allows you to make use of printer profiles. Now you have a number of alternatives here.
a/ You can make use of the printer or paper manufacturers "canned" profiles. These are generic and can vary. In general I have found the Ilford and Hahnemuhle ones to be very good.
b/ You can make use of 3rd party custom profiling services. If you only use a limited range of papers and stick to the same ink, then this can be a very cost effective way of custom profiling. It involves printing a test target, sending it off by post and then you receive the custom profile back a few days later.
c/ Buy a profiling system and do it yourself. The ColorMunki is such as system. It also doubles as a calibration device for you monitor. But it's not cheap, at around £325.
Again if you are going to Focus you could check this out.
Hope this helps
John C
