The ratings from users on cpap.com for machines I believe are true and accurate. They have also provides sales rankings. Lately, on my search I have been paying attention to craigs list or cpapauction.com for rare awesome deals.
The humidifier makes the air "softer" and a warmer. I turned mine off all summer and only turned it on last month when the air got dryer. It was a record year for rain; the first time I turned it off for any length of time. Definitely nicer with the humidifier on. Ever had a dry pained nasal cavity? That stops and everything is normal in the morning. On the flip side, if set too high you get a bit moisture in the mask spitting at you (called rain). It seems to be easier to get to sleep with a heated humidifier. Some machines will preheat the water before you start to sleep.
The software & readers gives you graphs and numbers, letting you know how you are doing. It is (or was for my old machine) a pain to keep going over the data. After a year, I stopped looking at it and have not checked in what feels like a couple years. I feel as if I am doing ok. If I had any concerns over the machine or sleep I would probably re-install the drivers and take a look.
And my machine is from '05.