Ok, the idea of setting up item cards like items on the shelf actually got me excited. I would actually spread them out (Hell, I could place them all around the room) and place them face down, so the players can take their time browsing and reading the "shop labels".
I plan my shops out thoroughly. I have different folders dedicated to each shop and print outs of every magic item they will carry over the life of the campaign. I keep the shops name, keepers name, voice and shop layout/specifics in a cover sheet for the folder. I bought the magic item card set from dmsguild and print em out. Easy peasy
This hits on two of your points, but when your player walk into the shop they feel a wash of tranquility. Any spell casters or people with proficiency in arcana make a check, anyone who succeededs sees the shop keep arguing with a metallic looking creature and a little old lady staring at you from the corner gesturing you to come near the glowing doorway she is in. If the player fails or doesn't make a roll the don't see the woman or the doorway. And they see the shop keep arguing with himself.
A Druid (proficient with herbalism kit) level 5 with Magic Initiate feat for cleric gets the cantrips mending and prestidigitation with the first level spell Ceremony. Crafts potions, antitoxin and holy water (from Ceremony). Casts plant growth on the 24 one mile diameter farms centered on a one mile diameter urban area (5x5 grid). Approx. 6 square miles total or 3840 acres or one hex. If the spell recreates our current level of agriculture (feed one person with 0.44 acres), then food and byproducts (leather, cloth, oils, etc.) for roughly 7680 medium creatures. A scribe Wizard level 7 casts Fabricate to make buildings. With Arcane Recovery, that is two 10 foot cubes of mud turned into 2000 cubic feet of bricks per day. A floored house 20 ft long x 20 ft wide x 10 ft. high of bricks (1 ft. long x 1 ft. high x by 6 inches wide), plus supports and a roof, is approx. 500 cubic feet of bricks. Four such structures provide a home. So from 260 work days per year, that is 260 homes. Ten of the structures are shops. The Wizard might be the Druid's spouse and could continue to fabricate more structures or defenses. Thus, they might attract 250 commoner/farmers with a spouse and children, or about 1000 citizens. Assume each farm has a number of farm animals, say a total of 2,600 additional medium creatures. The 250 commoner/farmers might be Expert level 5 faithful Sidekicks of the Druid. Each Sidekick would have 5 skill (2 of which are expert) and 2 tool proficiencies, as well as simple weapons and light armor for a militia. As skilled NPCs, they earn 500 gold profit per year (2 per day for 250 work days with two weeks of holidays) from 1000 gold in produce. Modest food with a gallon of ale is 0.5 gold per day per person. They would still provide food and other items for 4,000 additional medium creatures or about 730,000 gold in produce per year. Tax this at whatever you think is fair. The Druid crafts a Pitcher of Ceremony for holy water in one week. Thereafter, the pitcher makes one such vial per day. Also, a combination of 250 healing potions or antitoxin. The Wizard crafts 26 common magic items and 13 uncommon magic items per year (or twice as many scrolls). A level 14 Transmutation Wizard overlord can transmute up to 3.9 million gold coin (5 foot cube) into anything of equal value and fabricate this into useful sizes, i.e., gems or ore like diamonds, mithril or adamantium. The Wizard sells these to community shops. Good luck!