Hi again, everyone. I’m trying to figure out ways to speed up my modelling, so I have some questions in that regard related to coordinates. Is there a way to:

give multiple vertices the exact same X/Y/Z coordinate? Say two vertices are respectively at 11 and 62 on the X axis. I want them both at 3 on the X axis. Is there a way to change the value in the X box so that they both go to 3? Highlighting both doesn’t work - the mean/median (I don’t know which) of both vertices goes to 3 instead.

set multiple connected vertices to the mean/median X/Y/Z value in their set without changing it manually for each? I.e. if I select three vertices in a row, with their X values at 4, 6, and 8, is there some command that will set them all to an X value of 6?

make vertices/edges distribute themselves evenly without doing it manually? For example, if I have a cylinder and I move the edges around so that they’re varying lengths apart from each other, and then I need them equidistant to each other again, how would I (could I?) do that?

Use your snapping and pivot options to scale along axis.
If you want some element to be the reference for others, use active element pivot (alt+period), select that element last to make it active and scale to 0 along an axis.
If you need some other point in space to be the reference, place your 3D cursor in there and use 3D cursor pivot option. Snap menu (shift+S) helps to snap to objects and grid.

Snapping to mesh elements is also possible. Change the snapping type with ctrl+shift+tab and hold down ctrl and point your mouse cursor to a snapping target while moving your vertex or other elements.

For distributing vertices like that you could use to sphere with 100% influence (alt+shift+s, 1) or looptools addon circle option to make a circle. Looptools also has space option which distributes vertices equal distance apart.