Fox are probably the only people who put it on the box.
Warm water is better as it makes the line more supple so it sits on the spool better.
Because the spool can roatate in the bucket of water, less twist is imparted as you spool up.
Also, wet line packs down better...to do with less friction. have u ever noticed that if u put dry line on, after a few trips, even though u may have not lost any, there seems to be less on the spool...