DEC = Decimal
HEX = Hexadecimal
RR gives you both for the benefit of those that use them, liked them or program real radios with them. If you're using Windows OS, the included calculator can convert between the two and more.
Yes, it is possible to program only the ones you want and you should only have to worry about the Decimal ones when programming the Pro-94 or any scanner for that matter.
If I remember correctly, on the Pro-94, once you program the DEC ID's that you want then you can SCAN not SEARCH the bank, that way it'll only stop on the ones you programmed.