I run 2 swivels in my rig. Nanofil to swivel to shot line to swivel to leader.
I haven't lost a float in a loooong time with this setup.. Unless there is a nick in my mainline, the leader/shot line always pops first.
As long as the reel doesn't get wet, it won't freeze up. Although if it does, it will be a block of ice.. Happens to the guys on the rivers in the winter float fishing...
Swivel above the float, slip floats, Wallis cast or using braid are all ways to avoid line twist.
I run a swivel above my float with braid, no line twist issues ever....