Yep the wiki's guide is kind of unwieldy. But it does cover a LOT.
The mod you describe basically consists of 2 reactions, 2 new items and 1 new workshop which is pretty much doable once you familiarize yourself with the process. I would personally start with the reactions since they can dictate some of the tokens you might need to add to your items.
There is a good
guide on reactions too ( if you haven't read that already) but I would try to give you a quick example on how one of your reactions (the one for gears) should be:
[REACTION:WATCH_GEARS] <- that's the reaction's id
[NAME:make watch gears] <- what you see in game in the workshop
[BUILDING:WATCHMAKER_WORKSHOP] <- This is the building's id not the in game name
[REAGENT:A:150:BAR:NONE:NONE:NONE][METAL_ITEM_MATERIAL] <- reagents are your input material, you can use more than one reagent if necessary. Be mindful of the quantity.
[PRODUCT:100:1:ITEM_TOY:WATCH_GEAR:GET_ITEM_DATA_FROM_REAGENT:A:NONE] <- Note I used ITEM_TOY. That's because I think what you want to make fit that category better than say tools or instruments, it also means when you define your new items they have to be define specifically as toys.
[SKILL:WATCHMAKER] <- The skill that is used when performing said reaction. AFAIK you can't really make new skills (in this case "WATCHMAKER" is wrong) but you can use the already existing ones. Metalcrafting seems fitting to me.
Using the above as a template and changing the reagents/products accordingly you can make the reaction that creates your watches. All that's left is to make the items, the shop and then edit your entities so they can use them. Good luck on your modding.