I'm also a newbie and I've owned my BP25DA for over a decade. You can look for reviews online to determine the dates of production (as an estimate). I believe it was produced right up until it was replaced by the BP26.
As far as the MM module goes, I have one in my B100-SST, not in the BP25. I really like it and I purchased this particular B100 because it was embedded. If I were purchasing today, I would probably buy a BP25MM/MC vs. the BP25DA. The B100 only has a MM module; no MC. Nonetheless, I really like the performance of the MM module of the B100. I don't think I would have been able to purchase a comparable external unit at the pricing I got my B100 used.
Regarding MM vs MC, don't overlook the potential future desire to move to a MC cartridge. Without MC capability, you will be limited to high-output MCs or you will have to use a step-up transformer (SUT). I use a low-output Hana SL cartridge now and it's far better than the previous MM elliptical cartridges I used.