Q1- can’t answer, depends on your plant. But I feed the same ppm from about 2 weeks til I flip
Q2- strongly recommend you don’t use a 5g pot unless you intend to grow a 12’+ tall plant. 2g is plenty big for coco. Big pot will only bring big problems, especially as it relates to watering.
Q3 - see above kinda. Big pot, small plant = issues. But in coco, you should have some runoff daily once the roots fill out the pot. But again, by the time you fill a 5g pot you are gonna have a 10’ tall plant…
NEVER let your coco go dry. Daily feeding (multiple times per day preferred) daily dryback, but never dry.
good luck!