The pothos has this white stuff on it and the new growth looks deformed.
This is most likely Mealybug.
Neem Oil can be used to treat this insect.
Here are some articles that will help you.
https://www.gardeningknowhow.com/plant-problems/pests/insects/mealybugs-control.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
https://www.gardeningknowhow.com/houseplants/pothos/pothos-plant-care.htm
I want to spread out my plant so it hangs over my book shelf. How should I do that?
You will just have to have a bit of patience.
In time your plant will began to trail.
Here is a link with care information.
https://www.gardeningknowhow.com/houseplants/pothos/pothos-plant-care.htm
Can I pinch out growing tips to make more bushy? I think it is a pothos cause of variegation.
Yes, you can prune back your plant to rejuvenate it.
Trim any long and leggy vines. Cut with a sharp scissors at the point the leaves are connected to the stem.
You can then root these cuttings and grow more plants.
Here is a link that will help.
https://www.gardeningknowhow.com/houseplants/pothos/pothos-plant-care.htm
Could I propagate the stems that have no leaves at all! Just put them in root tone and then in water until they root? Have great lengths of the stems and hate to throw them out as they are vital and green. Thank you.
If the cuttings have the leave nodes, the little bumps on the stems that leaves attach too, they should root.
This article will help you.
https://www.gardeningknowhow.com/houseplants/pothos/propagating-pothos.htm
Why do some of the pothos leaves have brown tips?
This article will help you:
https://www.gardeningknowhow.com/houseplants/hpgen/botany-911-first-aid-for-ailing-houseplants.htm
I am trying to start my running pothos plant with a stick in the pot with so many fails - yellowing, root rotting, or just not growing.
From experience it can be difficult to train or keep a Pothos growing upright onto a trellis.
They just tend to be happier trailing down.
If you still want to try to train it upright. I would use a trellis and you can attach the plant using plant ties.
Plant ties that are soft and can be twisted around the plant stems without harming the stems can be purchased at most garden centers.
Here is a link with care requirements of Pothos.
https://www.gardeningknowhow.com/houseplants/pothos/pothos-plant-care.htm
https://www.gardeningknowhow.com/houseplants/pothos/pothos-leaves-turning-yellow.htm
Can a pothos harm an alligator?
Pothos is listed by the ASPCA as toxic to dogs and cats.
Also considered toxic to humans with irritations to the mouth and can cause stomach irritations with more severe problems possible.
Best to keep all pets away from Pothos.