What are these tiny things on the stems? Looks like some sort of pest.

Aphids are more likely to sit in low light, by soft foliage/stems. Scales tend to appear on maturer stems.

I dunno, I can't see structure from those pics. No idea if those are aphids (well, they don't seem to behave like aphids, looking at their placement, sparseness) and kinda just look like blobs. Might even be scales.

That is a white Aphid. They eat plant material. Not a good thing to have breeding in your garden. Though fear not nature has your back. Go on your computer or phone and amazon and order as little quantity as possible of Live lady birds they are very cheap. Unleash them on your plants and boom you have just started an extermination. Lady birds or lady bugs can eat up to 50 Aphids per day and can live up to 1.5 years with a good food source :) plus they are cool too. These little critters can spread like wild fire i would be very cautious about how you precede. though this is your plant you do what you want :) Best of luck you can use neem oil to deter them I think.

ALSO. Since plucking those 3 off, I have searched high and low across the entire canopy and haven't seen any other ones. I'm sure I could have overlooked a couple because that's a lot of foliage to scour, but I made sure to be as thorough as I humanly could. I'm not incredibly worried about these since I haven't spotted another but I'm very curious as to what they are.