Yeah you have to clean the edge of the tile with a small putty knife then put the clip in. And yeah it’s a huge pain in the ass and you will def chip a tile or two trying to get it clean. It’s just so much easier at the start takes 15 secs to wipe it rather that 15 mins carefully scraping

Run 8/3 Romex in conduit. On you main feeding your sub put a 40 amp breaker. Your sub can be a 100 amp no problem cause your feeding it with a 40 so it’s technically a 40. If you wanted to do it cheap buy 12/3 run it on a split 20 and that will do what you need at 1/4 the cost. No sub panel needed just run direct to plugs and lights but get 20 amp plugs and switches

Check the dial at the bottom. I once rubbed against it and turned it way down to like warm instead of hot

Eventually more like already and has been for some time usually when it’s a big storm that just over loads it and leaks a lot were there the whole time