I usually do 2 transplants with my seed grows, from solo cup to 1 gal and then to 5 gal now that I grow in coco (in soil I went from solo cup to 3 gal to 7 gal).
I find transplanting to appropriate sized pots makes for faster plant growth and easier watering practices, with my transplants I can water to runoff every watering, where if you went from solo cup to 5 gal, you would not want to water to runoff as it’d take a really long time to dry up a bit (small plant in big pot syndrome).
Yes I would.
I find 5 gal pots are fine for coco grows and most growers would even be fine with 3 gal pots, specially if not growing giant plants like I do - my plants are usually between 5-6 feet tall at harvest.
Yes. I went from plastic pots to fabric pots and then from fabric pots to mesh pots, each was an improvement over the other. I love the Rain Science and Radicle mesh grow bags/pots. Fabric or mesh pots will allow more oxygen to the roots, mesh being even a bit better than fabric. Also allows the media to dry up a little faster to avoid over-watering problems (though not much of a problem in coco - specially with perlite in it).
The one pain is transplanting out of fabric or mesh pots so many do solo cup to 1 or 2 gal plastic pot and then into fabric or mesh for the final pot.
Tag me in your journal and I’ll answer any questions you have.