Recently finished upgrading to a 200A panel and replacing all the
wiring in the house. Instead of Al entrance cable I used 2" conduit
to get from the meter to the panel and ran copper feeds to the panel.
The electric company replaced my old ham slicer meter with a digital
meter.

First, can I putty or caulk around the wires inside the conduit to
stop the cold air from coming in?

Second, my electric bill is up about 15% since I started. The only
additional load I added was six 75watt bulbs on two dimmers that
replaced one 100watt table lamp, these run 16 hours a day. Also three
hard-wired smoke detectors. Are the digital meters more accurate? Is
there a way I can test the meter?