I'll chime in on what I can here. I'm in the same situation. Just had my Alpine (150 model) installed last week with a Burnham 50 gal IHW tank.
I haven't played with the numbers and the ODR. But it was 36 degrees the other day and it was running at 135 which is close to what you have.
I have my DHW setpoint at 180 (default). I have no mixing valve installed. As per the manual, when the tank calls for heat the only pump that should be running is the IHW pump (no zone pumps, no boiler pump, no system pump). So I have set the options to that. The DHW should be wired to the boiler because if it is wired to the taco box the boiler would not be able to tell the difference between a zone and the tank and respect to temps. The boiler computer controls that.
My boiler keeps cycling up and down when heating the water. It heats up to ~180 and then runs until the temp drops. Then cycles up again. I'm reading that it's supposed to do this but still seems kind of odd.
I'm more positive on the piping in my system, I just wish the book was more robust in helping to set the system up. I'm doing it on my own and it's a bit confusing.