fill your vessel up with 2-3 gallons, make sure the element is below that. It does not need to be on the bottom. When I did my keggle, I did it the same level I put my pickup tube, but a keggle has a concave bottle. I dont use a false bottom. I use a hop spider and a circle of stainless braid on the pipeup tube and I leave a ton of break material. If you try to whirlpool and expect a tied trub cone, I have not been able to get one with my element in the keggle, not sure if it interfears or using a hop spider I dont have heavy enough material to form the cone.
If you get a punch, make sure it is a chassis or radio punch, not a conduit. Conduit 1 1/4 hole size is actually 1.32. I can let you borrow mine if you want, I have the hole saws and the punch.
Kals element is different, but the process should be identical. Elements are either 1" or 1 3/8" threads from what I have seen. I think most are 1".