The spin-on filter thread insert is plastic on the oem filter, that is what can crack. If this is the first time changing that filter, they are on super super tight, and you may end up destroying the original filter to get it off. The new filter will come with a new thread insert, and it does NOT need to be reinstalled super tight.
And, yes, the seal for the sump filter is just a ring that presses into the trans body, and it is a booger to get out, after quite a few filter changes on mine, the ORIGINAL seal is still in place, I just reuse it every time.
There is no need to let the fluid drain for an extended time.
As to making a mess when draining the pan that has no drain plug, you use a LARGE drain pan, I use to use a large rectangle poly storage container as a drain pan, then you loosen all the pan bolts, then take them out from one end of the pan, letting the pan droop down so the fluid drains from that end before taking the rest of the bolts out and dropping the pan down.
And, adding a drain plug or replacing the pan with one that has a plug will make the next change much easier.