I'm based in Europe and my dryer is a 1 phase unit so it takes no more than 2300Kw all included (also the rating of the fuse in breaker/fuse panel). Also here it's required to have a earth leakage relay, that if the current that goes in the relay does not match what goes out disconnects everything from the outside, it only allows 20 miliamps of leakage max. in practical terms it means that if current goes through me to ground the relay will cut. and all stuff like dryers and washers are required to be grounded. anyway i would never touch anything thats live if i can avoid it. and if needing to messure something good commons sense is half the safety
I do have the background, been working 1 year as an electrician and do have about 12 courses in electronics. The Schematics are not included... but that not what worries me, i can draw it in a few hours with the dryer taken apart and a multimeter.
For the high loads, in fact both the heating element and motor that rotates the drum its my plan to use solid state relays or triac's. I have in mind those kinds that have either screw terminals or spade connectors depinding on what is used in my unit. 40A seems a bit overkill compared to that my system is 10A max.. but maybe go for a 20A would be the choice. since my dryer is a condensing type it has 2 airways.. one internal and one that just takes room air and blows it through the condenser, the output from here is barely any hotter than what it takes in and seems a good place for airflow over the heatsink. i agree to not mess with drum rotation, makes no sense to alter it.
and the idea with multiple temp sensors is not bad either, at least i know there has to be a certain difference between room temp and the temp in the drum before the condenser operates, the higher difference the faster you are done but also you use more electricity. i know that my dryer has a resetable thermofuse if it gets to hot. i only need to figure how it detects a full filter.
my biggest problem is coding, no problem in finding code here and there for what i want, its more stitching it together that is the main issue.