G'day Azrael, glad you joined us here in our little haven from RL (real life)!
DE are indeed a many-faceted army, each variation with its own unique and powerful character. It really is a lot of fun.
Re: 40K abbreviations, here's a few for you (although you probably know most of them already). You can often Google them, as they are a common question on most forums:
MEQ = Marine equivalent, other army's units with the same statline.
GEQ = Guardsman or Guardian equivalent units
TEQ = Terminator equivalent
DT = Dedicated Transport
FA = Fast Attack
HQ = Headquarters
HS = Heavy support
AV = armour values ( for vehicles)
BRB = Big Rule Book, the official 40K rulebook from GW
CC = Close Combat or Assault, can also be HTH (Hand-to-Hand)
CCW = Close Combat Weapon
IC = Independant Character, usually a HQ choice
KP = Kill Points
LOS = Line of Sight
MC = Monstrous creature
RAW = Rules As Written
RT = Rogue Trader, the first edition of Warhammer 40k
VP = Victory Points
WD = White Dwarf, GW's official magazine
WYSIWYG = what you see is what you get
Cheers.