I found that as humidity spikes, I get binding in only a few places using the sharpie runoff test. Super light passes with a scraper, barely taking off anything on the OUTSIDE ( away from the blade side) gave me the space I need. When using a sled, I apply slight hand pressure toward the blade, like one would when running against the fence. Only taking material off of the outside keeps the registration surface on the side I'm pushing toward the same through seasons. May want to give a slight modification before tearing the runners off. I've never been able to get new runners on a sled to be as tight a fit as the off coming set.
"the essentials" is a loaded question as that depends on your approach. If it's all hand tools, that's one way, a power tool guy is another. Most of us here are a bit of a combination of both. You have to be able to dimension lumber first. Table saw, jointer, and planer accomplishes that task. If you're a hand tool guy, then it's saws and planes. You'll also need the basics like layout tools, drills, sanders, etc.. From there, there's a number of other items that greatly enhance your ability to create the kind of stuff you want to build.