If it is too much light, it's not extreme. "some" node spacing is occuring... as long as that is healthy, it's fine in regard to light. when extreme, the leaves push on each other and they point upward ... when it happens to a seedling it's painfully obvious. The yellowing up top could be slightly too much light or not providing enough nutrients. Need more info.. is this soilless? soil? have oyu fertilized? how concentrated was it? etc etc.. these things will all help you rule out one or the other.. if you adjust the light, make it a small adjustment. much easier to use size-approriate pots. Under normal circumstances with a properly constituted medium, watering is not a concern and quite easy.. 1) fully saturate (10% runoff, religiously, if it is a soilless context) 2) wait for appropriate dryback (plant drinking) and repeat. Loss of weight is the best trigger, but depth of dryness at top of medium works too. in a too large pot, you can can't do that. you have to water a smaller column around the plant, but make sure that moisture goes all the way to the bottom or else you train roots to grow superficially with a fucked up drying pattern. Roots physically grow toward greater moisture... watering properly ensures greater moistures is downward, not toward the surface. properly constituted - a high water-capacity soil should have 50% perlite or similar per volume. Something that holdsless water, like coco, only needs 33%. Each comes out to a similar gas:water mixture per volume, which is what matters.. not whether it's absorbed into coco or some other solid. Being a bit off is not a problem.. .if not ideal, can still grow healthy plants. If a plant ever droops after a watering, that's a sign of a poorly constituted medium. Again, shouldn't drail a grow, but certainly slows it down, and easily avoided in future.