Bunch of condensing boiler questions

Hello, I've read many threads but still confused about many aspects of condensing boilers. Really looking for help here! Long story short, bought house and the tank and boiler decided to leak within the first week. Got several quotes for new heating system and ended up getting a Lochinvar Knight 110,000 BTU mod/con boiler with indirect 40 gallon tank (Heat Flo). While I understand that the modulating part of the boiler is already saving me money (I'm on propane and the old boiler was 164,000 BTU cast iron unit), I am very confused about how the system should be setup to utilize the benefits of condensation. Everywhere I'm reading that the return water should be 100-130 F range for the condensation to occur and the delta T should be 20 F. When my boiler is running even on one zone - it's typically showing delta T of only 2 degrees and the return and supply temps are in 150s or 160s. Does this mean the condensation doesn't occur? There's also a third temperature the display is showing - flue temperature and it's usually in 120s, but I think this might be in the pipe that vents to outside? When the system was installed they said that for baseboard fins to open up they need to be running at 180ish and that's what he set the temperatures to be, but then for me to get 120-130 F on return water it sounds that it would be impossible to achieve. I guess the question is - if I lower the temps to the point where condensation can occur - would that gain in boiler efficiency outweigh the lost efficiency of baseboard fins? Would it also take much longer to heat up the house? Sorry if this doesn't make sense, I think I have a quite a mess in my head from a week of reading online resources and talking to installers. Hopefully, folks here can help me straighten everything out. Few details about the house: about 2,400 sq ft, three zones (typically, only one or two at most would be used at the same time), we are in Massachusetts. Attaching a photo of display on a "typical" boiler run and photo of plumbing (I think they've installed some primary/secondary piping here, but I am not clear on details at all). Thank you very much in advance!