G'day KibaOokami. Welcome to Apnea Board.
A good place to start is in the Apnea Board Wiki, which will give you lots of information:
http://www.apneaboard.com/wiki
See also the helpful tips to ensure success:
http://www.apneaboard.com/wiki/index.php...re_success
To answer some of your initial questions:
xPAP pressure is measured in centimetres of water. 23/19 cwp means an inhale pressure (IPAP) of 23 cm H20 and an exhale pressure (EPAP) of 19 cm H2O. To imagine the amount of pressure involved, fill a tall glass or jug with water, insert a straw 19 to 23 cm (about 7.5 to 9 inches) and blow bubbles. That's the pressure you'll be working with. It's not enough to blow up a balloon, but it is enough to splint your airway open to stop it collapsing. There is an excellent animation called
Understanding Sleep Disordered Breathing on the first page of the wiki which shows exactly what happens during sleep apnea.
That prescribed pressure is a bit higher than we normally see, which makes me wonder if you have simple apnea or whether there are other breathing issues in play, such as asthma, COPD etc? Do you have a copy of your sleep study report? (If not, you should obtain it and a copy of your prescription for your ongoing records). If you wish to share that with us it can help us give you any specific advice you might want.
Regarding the type of machine: The two main players are Resmed and Philips Respironics. Each of them make a range of bilevel machines, aimed at differing breathing conditions. The Resmed bilevels are called Aircurve in the US and the Philips will have the word BiPap in the name. Philips and Resmed are both good brands, and it's a bit of a Ford / Chevy thing as to which one you prefer. Having said that, some individual Philips machines have features not found on their Resmed equivalents, and vice versa. In particular, the Resmed Aircurve ASV is generally regarded (by us here on the forum) as distinctly superior to the Philips equivalent. As you which particular machine you get, that will depend on whether or not your have plain obstructive apnea or central apnea (or mixed) and whether there are other factors such as COPD or other medical conditions.
I know that's a bit of a mish-mash of information, but if you can give us a better idea of your situation, then we can provide some more specific information for you.
One other thing to mention is that the mask will be the hardest thing to get right. Everybody's face is different and there are dozens of different mask makes and models out there. You need to find one which is comfortable, fits properly and doesn't leak. Ensure your provider allows you to try on several different types and has a return policy - what feels OK in the office may not be OK in bed at night.
Hope this helps.