The small bumps on the stem would develop into roots if they have appropriate conditions.

You could have mealy bug, which loves (love) too-wet conditions, and you need a fungicide (house plant drench) to get rid of it, then you need to repot into a much faster draining gritty soil mix without peat in it.

Those bumps belong there, they're normal on the woody part (as jean001 said), but the white, dusty-looking stuff doesn't look right to me...

I just repotted tonight, and found these little white bugs EVERYWHERE in the soil! They look like tiny little white gnats. They crawled all over the place, and had wings it looked like, but they did not fly. I do have fungus gnats in some of my plants right now, is this what they look like between the maggot and the fully flying adult stages maybe? I had found these same things in the soil of my purple velvet plant which I had to toss. It is so discouraging to have all of these problems at one time!

Fungus gnats mean you are overwatering or using a soil mix that does not drain well.

Scheffleras need really bright light and to get dry between waterings.

Many repot plants when not necessary and have too much soil to rootball ratio which encourages all that soil with no roots to stay too wet.

That is not scale, you would know if it was. Scale is almost impossible to get rid of.When a plant is infested with scale, a sticky honey like substance drips and accumulates on the branches.The rim of the pot is sticky it is just gross! The bugs look like popcorn kernels. So take a deep breath and say "whew!"