A call to the provider to ask what machine they are planing to provide is a good place to start. If they suggest either of the above machines you will be fine, but you must be VERRRRY SPECIFIC about the model designations. Some aredeceptively similar.
If they suggest anything less talk to who ever is writting the precription and insist that they writ it for exactly one of the machines I mentioned plus your mask of choice and then write on the prescription "dispense exactly as written." Also when you pick up your machine have them turn it on in front of you and look at the display for total machine hours. This will tell you if you are receiving a NEW machine or a preciously used machine. You want NEW, less than 10 hours.
The mask is not so simple. Have you ever gone shopping for shoes with a woman? There are hundreds of masks from dozens of manufacturers, in many styles. In a room with 100 peaople you are unlikely to get a majority agreement on the best mask.
In a room with one person, me, I can't get agreement on the best mask. I can't tolerate nasal pillows. Some days I like my SleepWeaver Elan nasal mask, some days I prefer my SleepWeaver Anew full face mask, some days it is my Fisher and Paykel full face mask. Some days I don't like any of them and look for something new. I am also a side sleeper and I am younger than you only 68.
To recap, you must be very fussy about the machine it will be with for 5 years based on Medicare guidlines. The mask can be replaced every 3 to 6 months and most DMEs will alow 1 or several returns when you are first getting started.