Why did the first set of leaves grow so long?

could have more of a sativa trait with long skinny blades on leaves... or not. It might just be that those first 2-3 sets of leaves can be funky and the plant grows out of it. the inconsistent pigmentation could be similar... either just some early fugliness or your fertilizer is out of balance. If not fertilized yet, then the soil is out of balance or too hot etc. make sure "some" internode length develops and you should avoid any stunting. as long as you are saturating all the way down, you aren't watering wrong. wait for top to dry and repeat. if any problems arise from such procedures it is the fault of how the soil was constituted and nothing else. add more perlite if normal watering behaviour causes issues. you want 50% of volume to be perlite or similar (33% in coco because it holds less water per volume)

It's a weed, it will be fine. Your going to have to wait on it. Cold temp, food genetics all contributed to pace of growth. Sit back observe and enjoy. Learning is fun.

genetic, thats perfectly fine and nothing to worry about And im sure you overwatered your plant, so go a bit slower on the water, good luck!