So ladies... I hate to sound like to only one who doesn't know what's going on but I'm going to anyway.

Help me please with the abbreviations first.
DPO- Days past ovulation
CM- Cervical Mucus
CD- ?
POAS- Assuming preg. test or something but unsure
BCP- Birth Control
Can't remember them all, but if someone could point me in the right direction or explain for me I'd really appreciate it.
Now for the stuff I'm really, really want to know. Okay, so the first time I concieved it was a surprise. So I have no clue about all of these tests. I've learned how to do the basic calendar yesterday. Once I charted it all on Excel, I've notice my period shifts like every three months... So obviously, I should take be taking temps and testing for ovulation, and all that stuff. But I don't really understand all of this. First, I'm not sure if I should go the less expensive route on the ovulation kit thingys, buy middle of the road, or should I splurge and buy the one that does all the work for you. Which tests are the most accurate, what do you all use? Then checking my CM, and basal and such... Anyone can explain that would be cool. Or attach a link and I'll read. Then I was reading about this stuff called Preseed, anyone have any recommendations for that type of thing?
Any advise or tips are very appreciated... even for the stuff I may not have asked about.

Thanks Ladies