Slow oil leak, looks like main seal

[ProfessorX5]

I will get to display my extraordinary self control when I go see that thief of a dealer tomorrow. Went for an oil change, and the guys at the shop showed me that the car is leaking. It hasn't been enough to show on the dipstick, but it does look like it's coming from the main seal. I don't know much about cars, but I'm guessing this would be a nightmare to fix.

Since it's a really slow leak, is one of those 'stopleak' additives advisable (worked for me on another car which I drove for a long time after with no further trouble)?

How long should the job take an indy shop to do? Shops here vary from $60-150 an hr, and I might have an in-law I can use to do the work.