Buying a CO2 tyre inflater I am thinking about buying a CO2 tyre inflater. I have never used one before and have 3 questions:


Do they have enough pressure to get a road tyre up to full pressure (~100psi)
When you use a cartridge, do you have to use the entire cartridge at once? 
Are there any common cartridge standards? i.e. am a better off going with a particular brand because it is compatible with more brands of cartridges.. or are they all happy to mix and match?
Yes, this is no problem, though I would suggest practicing once before you have to use it on a flat. The first couple of times I used an inflator I had trouble inflating my tire fully.
No, but I've found that once I start a cartridge it will leak slowly, so it doesn't last forever. In my experience it doesn't last more than a few hours, certainly not more than a day.
You can buy inflators that handle both threaded and unthreaded. For example, this one -- http://www.amazon.com/gp/product/B00278XO0Q -- can take any 16g CO2 cartridge.