Purple coloration is common in low temps. I don't really see a problem- seedlings don't all look perfect all the time, lol.
Run coco at a pH centered around 6.2/6.3. It's soilless.
You can run MH from the very start- that is not an issue unless you can't maintain temps or soil moisture.

Can we please not discuss any storks on open forum? Thank you. It's been a problem all along and has been getting out of hand lately.