Just to answer your question quicly, plant 1 seed per cup. Don't plant more than 1 seed per. pot, or the roots will get tangled below and seperating is near to impossible withou certain death.

A 60W lamp? I take it that is a regular household bulb? If so, it is no good and won't get you far. They do not create the correct light spectrum.

Your seeds sprouted because during germination, the seed doesn't need any light, so now that you have a sprout, you need to switch to proper lighting, and a 60W regular bulb won't do it. The plant will stretch and stretch for proper light until you get it.

Do not switch from inside to outside like that. It stresses the plant out and it is not good for it. Keep it either inside or outside. If you bring it in at night time, cover it with a blanket or something so that it is dark.