You do want UV exposure either from the sun or a bulb. Some say 5-10 mins daily of sunlight is sufficient, but it must be direct sunlight, glass will filter out the UV (and most of the IR for that matter) so being by the window does not count, unless it is open.
You'll need a true full-spectrum bulb, NOT a daylight-balanced bulb, meant for use with birds. The true full-spectrum bulbs have special coatings that emit the UV light. Unfortunately, those coatings wear pretty quickly so you also have to replace the bulbs every 6 months and they aren't cheap. I posted some info about one of the brands available here:

. You do need to place the bulb near the cage, but not in it, and you don't want the bird to be able to make contact directly with the bulb. They don't run particularly hot, but you definitely don't want them chomping on it.
It is generally not recommended to use vitamin drops unless a vet recommends it. Put in the water, they can cause the water to get contaminated more quickly than normal, so you'd have to change it several times a day. A good pellet should contain most of the ingestible vitamins that drops would provide anyway.