the fan can be anywhere as long as its not pointing at the leaves, it can strengthen stalk or could be used to keep heat from the light away from the plants, pointing away would also work to circulate the air around the plants.
3gallon buckets are good size, u will want a soil with pearlite in or u could add pearlite as its good for drainage, if ur buying a pre mix then stuff like peat, pearlite, bark, worm castings are all good.
for nutes get gh or ff or something like that, give quater strength for first feed then half strength for 2nd and after that go to full strength, it should say how much to use on the bottle or u can find the info from the manufacturers website probably. different feeds used for veg/bloom also a boost for increased yield used in bloom stage and a flush for use in last two weeks.
you should start using them after a couple weeks i think the plant is meant to have 2 sets of proper leaves or sumthin, but if ur soil has nutes in as many do then u may not need to feed for up to 4 weeks depending on what soil.