While some people do take to it easily, it has taken me years of constant learning and repetition to get to where I am. Think of this as driving a car, you are still in the learners permit lane learning to drive. Eventually you get a license. Next thing you know (or maybe you didn't follow my path and got there sooner), you are zooming along.
I believe strongly that sewing is a physical (even if not large muscle) activity that requires hand/eye coordination and quite a bit more upper body strength than some of us may have to do the quilting part. It's like any other activity, if you only do it once a year you get rusty.
Most of us try to buy notions on sale/with coupons because yeah, they can get expensive fast. You rarely have to replace them once you have them, but they can break if hitting a hard floor at just the right angle or whatever. Start looking out for coupons/sales because you will probably eventually want ones somewhere between 6.5", 8.5", 10.5", and 12.5" or bigger even depending of the size of blocks you make. I keep my smallest blocks pinned to a cork bulletin board, I think you mentioned you are a small space quilter so probably tuck them away in a drawer or your sewing kit for now.
To help get that seam allowance, there are magnets (which won't hurt even a computerized machine) designed to use on your foot plate to help guide your fabric. Pretty inexpensive I would think.
On my old vintage machine I used a fancy bandage of my son's -- it was blue with I think originally glow in the dark stars. I placed it rather close to the edge of the case using a piece of graph paper to get the true marking, and the little pad of the bandage helped me guide my fabric in.