Say I want to create a toon to harvest the skills of a profession I have no desire to play beyond said harvesting. Do hero's retain skills if I delete the toon?
heroes can use all unlocked skills. unlocked skills are account-based, not character-based. once a skill is unlocked on your account it will always be unlocked for all heroes and pvp characters to use (and for learning through skill trainers/tomes).
Yes, skill farming is a great way to unlock basic skills on your account. I have done is for most professions. If you are quick, you can unlock about 5-10 skills (about 5 regular and 2 hero) on a NF toon in about 30 minutes. Nothing great, but it gives you something to work with in PVP and Heroes.
Not to mention about 500 gold. A nice little bonus.