First, most reviews I've read on tuners all trash the tuner software, like WinTV and MythTV(something like that?), and whatever else, and Windows Media Center is like the most applauded one.
Correct, the software that comes from the tuner MFR is garbage, like WinTV.
You want to use third party DVR software like:
Windows Media Center (Comes with windows depending on version)
MythTV (Free/Open Source)
Windows Media Center do recording? And will it work with an IR Blaster
Yes, All three mentioned above will manage your recording etc.
Will they all work with a given IR blaster? Depends. Make sure there are drivers and check.
And then I'm left with, do I need an analog tuner or digital
tuner since its coming from the STB?
You will probably only need an analog tuner considering the STB is actually doing the tuning for you. You are just taking an analog signal from the STB and putting it into the tuner; whether it be via S-Video, Composite, Component, etc.