I’ve spent a day pulling my hair out on trying to use Sketchup, and I still can’t figure some extremely simple things out, and after 7 hours I can’t do this anymore.
I’m trying to draw a simple rectangular speaker box with some circular holes. Here are the things that I want to do but I can’t no matter how much I Google.

I’m trying to cut a hole in the front and back side for every circle I’ve drawn, but push/pull just will not cut a hole.

I’m trying to draw a circle with the top and bottom truncated. Basically I want to turn a circle and truncate it to look like this
However I can’t draw a straight line from a point on the circle to the other point on the circle. It would snap to a different point that makes it a slanted line, but not straight line. I want to do this for the outer circles in the “tweeter” and “midrange” group.

How do I find the center of a circle?

How do I move the center of a circle to exactly say 1 cm to the right and 2 cm to the bottom of the top left corner of a rectangle? I need to draw a to scale model, and I need high accuracy. For example, the two circles on the front and back needs to be in the exact same spot so they’re perfectly back to back.
I’d really appreciate any help for this. I’ve uploaded what I have so far.
Speaker.skp (56.5 KB)