I used to run a small engine/powersports business, before that I built racing go kart engines. Did most of this work with pretty basic tools and sold lots of high end modified engines to happy customers around the country. Honestly, I used a cheap set of telescoping gauges and a HF digital caliper for most cylinder measurements. Never touched a micrometer or needed all the fancy kit I have now.
If you're just doing rebuilds for garden equipment most of what you're asking about is overkill. If the cylinder is far enough out to need reboring you'll be better off replacing the whole engine. Of course what you want to do, and what's required might be two different things. I'm just saying, in my kart engine business the lathe was mostly used for cleaning up valves and I didn't even have a mill.
John