I just have a cheap humidor box kind of like this one
https://www.cigarbid.com/a/onyx-glasstop-humidor/3646237/I replaced the cheap humidifier disk with a better gel based one like this
https://www.thompsoncigar.com/p/xikar-crystal-humidifier/97982/#p-191436&utm_source=connexitythat you can charge with regular water or the specialized xikar solution.
The build in analog hydrometer that came with it is pretty accurate, but I got a cheap electronic one to doublecheck like this
https://www.amazon.com/dp/B07QC7JRDP/ref=cm_sw_em_r_mt_dp_U_7ZFiFbF0W0HXXI usually buy sample packs off cigarbid, so can generally keep everything I have in my humidor, but for people that buy whole boxes you can store them in expensive humidors like seen in posts above, or some people just get good airtight plastic bins and use their own humidifier and hydrometer to keep tabs.
As far as being able to tell if a cigar is at the proper moisture to smoke when you get it shipped in, it's really just trial and error till your fingers understand what resistance is a good one for each cigar really because different brands and types have different feels. Take note how different cigars feel that you know smoked good and keep that in mind for that brand and cigar
7nine