Coco requires a little more magnesium than regular soil. As far as nutrients go start very light at 2-3 weeks from seed. 1/4 recommended strength every third feeding. When you see significant growth starting bump it up to 1/2 every third. Every strain has different in its nutrient intake. If you start seeing the bottom leaves turning yellow feed more until your at 1/2 every other feeding or full strength if your comfortable with it. If you see dead brownish tips cut back on nutrients a bit. Calmag can be added at 5-10 ml a gallon in-between every other feeding. Flowering calmag is good just cut out all nutes 2-3 weeks before harvest. You can change this when your more comfortable but this will get you there.
No and yes. Clones skip the seedling stage and go right into veg but they still need to produce roots. Start slow like a seedling but clones will have a rapid rate of growth compared to a seedling once rooted.
If you have 3% runoff your good. Just make sure your pots are dry(not bone dry) between watering. If your underwatering your going to have more runoff because the water goes right through. Overwatering, nats, curling leaves, root rot ext. Just lift the pot and see if it's lost most of its water weight. Probably every 3 days depending on climate for 1 gallon.