I recommend buying some WAGO lever-nut connectors to make your electrical boxes that much cleaner and easier to service and test. They are expensive compared to wire-nuts but you only need a couple per box. https://www.amazon.com/Wago-Lever-Nut-Assortment-Pocket-Pack/dp/B01N0LRTXZ/ref=sr_1_1_sspa?ie=UTF8&qid=1528247336&sr=8-1-spons&keywords=wago+lever&psc=1
> but I needed (wanted) to use the connectors
Can't fault you there. They look pretty awesome. I added the my Amazon cart for "later" hoping something will come up in the near future where I can justify ordering them.
I ordered these Wago connectors a few weeks back and I'm just waiting for an excuse to use them.
I use these Wago wire connectors instead if wirenuts flir the past 3 years after having an I same amount of service calls for loose wire in a wire nut(not my installs) they have been great.
Wago 221 Lever-Nut Assortment Pocket Pack https://www.amazon.com/dp/B01N0LRTXZ/ref=cm_sw_r_cp_apa_i_wGYsDbZ1HZ5RY
If they are all on the same breaker you should be able to wire them all into one smart dimmer. (probably keep the exhaust fan separate) Most likely you would put all the blacks into one wire nut with a jumper coming out to the new switch, all the neutral's into one nut and do the same, and then same with the grounds. this many wires coming together will be a bit of a mess so I prefer these instead of wire nuts https://www.amazon.com/Wago-Lever-Nut-Assortment-Pocket-Pack/dp/B01N0LRTXZ/ref=sr_1_1_sspa?ie=UTF8&qid=1518965173&sr=8-1-spons&keywords=wago+lever+nut&psc=1 You could buy a new trim cover then with blanks in it to get rid of the extra holes. However not sure if they are all on the same breaker or if there are any unusual circumstances why you couldn't do the above.
I use Wago 221's for these kinds of temporary things. They don't damage the wires and give a quick, easy and excellent connection.
https://www.amazon.com/Wago-Lever-Nut-Assortment-Pocket-Pack/dp/B01N0LRTXZ
Wagos are simple electrical connectors like nuts
I wouldnt focus on the color- I think that varies by manufacturer. Your wires are most likely going to be 12 guage. Do just buy an assortment pack and use the one that's appropriate for the number and guage of the wire you have. If you want to make life easier, grab some of these this style: Lever-Nuts
Once you use them, you'll never go back to wire nuts.
Ignore the sonoff stuff. That's chinese junk, not UL-listed, burn-your-house down kind of thing.
Best and most cost-effective way to do this is as follows.
1) Put a single gang box in-line with the 120V wire, so between the transformer and the incoming 120V wire. If you don't have enough wire, disconnect it from the transformer instead of cutting it, and run a second length of wire from the box to the transformer. This can be concealed under your cabinets, assuming that's where the transformer is.
2) Install a Lutron Caseta Smart SWITCH (not dimmer) in it, wire it to control the transformer. WARNING - this is only good up to 6A / 700W. I'm assuming your transformer is less than this...but check just in case.
3) Pair it with a Pico remote, wallmount kit for the Pico Remote, and a claro wall plate
https://www.homedepot.com/p/Lutron-Claro-1-Gang-Decorator-Wallplate-White-CW-1-WH/100093841
All UL listed and safe.
No extra wiring for the remote switch (Pico remote battery lasts 10 years)
Bonus points -> The caseta smart switch pairs with the Lutron Smart Hub if you ever decide you want to control it with your phone too.
Optional step: Purchase some Wago 221 lever nuts so you don't have to screw (no pun intended) with those lame twisty wire nuts
The crazy DIY shit recommended on this subreddit blows my mind. Y'all burn down your houses if you insist.
EDIT: In case you're located in Canada, you can find all of this stuff at Home Depot Canada & Amazon.ca too.