While other things can cause heart problems, high blood pressure, etc. Sleep Apnea (SA) most DEFINITELY can cause these problems and more. SO glad you are getting tested and getting treatment under way.
It is SO important to get a good, data capable machine. Without the SD Card that can be pulled out of the machine and put into a computer there is no way to download the data into a program, such as SleepyHead, that will let YOU know how YOU are doing.
I do understand about confusion with the diagnosis you have just received; it is a lot to digest all at once.
Some info from my personal/family history on Sleep Apnea:
My father REFUSED to use any and all APAP/CPAP,BiPAP and any and all masks; he ended up having a heart valve replaced and, about 3 yrs after that, fell asleep over his dessert and died in his sleep. He had extremely severe SA with Periodic Limb Movement Disorder (he looked like he was trying to race in the Tour de France) and, by the time his SA was diagnosed, had already given himself dementia - lost his drivers license and was declared legally incompetent, I became his Legal Conservator.
So, please, read and digest all the info you can - if you don't "get it" the first read through that is OK! Keep at it and stay with this forum.
Diagnosed: 44 AHI when supine, O2 down to 82%
Treated since 20 Sept 2014:: 0.7 AHI, Settings 7-15, EPR on Full Time at Level 3
Better living through CPAP/APAP machines!