I'll try and answer what I can.
The Excal is more expensive partly due to the additional components and milling required for the 2 solenoid system.
Excals are dual solenoid, originally MACS now Humphreys and the Viking is single, same time line on the noids.
The Viking is faster than the Excal but the Excals tend to be a bit more efficient, 2000 shots off a 68/4500 give or take. Maintenance is nothing more that a couple drops of oil in the ASA and general cleaning. I've have both and Excal and a Viking and both are exceptional performers in every way. I'd say the biggest difference between the two is feel, which is entirely subjective, but coming from cockers the Excal just feels better when shot. Also try AKA owners in addition to PBN for information.