Hi there, Here are my views/ experiences: 1) Low voltage bulbs generally project less heat than line voltage. They also last longer (even much longer, depending on the bulb). A 50 watt low voltage halogen bulb is a little brighter than a line voltage halogen bulb. Low voltage cans are available in smaller sizes than line voltage. The con is that low voltage is more expensive- there's a transformer to buy. But taking into account the smaller size, longer life (up to 20k hours vs 2k hours) less heat projection and brighter light, I always go low voltage when there is a choice. Now, if you have 30' ceilings, that's a different story. But for most homes, lv works great. 2) Not really. Kitchens are very task oriented. So the cans will be closer together over counter and other work areas to give good overlap and eliminate shadowing. But over walkway areas, they'll be farther apart. 3) Cable and rail halogens do offer a lot of flexibility. You can not only slide fixtures to move them, but add more very easily if needed. There is also a design issue. What do you want to see on your ceiling? I have rail in my hall, but recessed (3" low voltage) in my kitchen. Basically, every lighting design I do involves low voltage cans. As I'm in California, I'm forced to use LED for kitchens and bathrooms. Which are great units. But in a design sense, the low voltage allows for the smallest hole in your ceiling without sacrificing brightness or coverage. There are always exceptions, but for the most part, you can light up a room using the same number of 3.5" low voltage halogens as you would with 6" halogens. The light would be the same (if not better) and the overall heat in the room would be much less.

I have 50w gu-10 bulbs (line) in my living room (Unknown brand bought at Home Depot or something). They are bright enough and they do work well with aperture trim. I also installed 37w Sylvania Tru-Aim IR (12v) in my kitchen, bathroom and dining room. Wow what a difference. Low voltage gives out a nicer light spectrum more comparable to natural daylight. (Not artificial like daylight CFL's). I forked out more for "IR", which has an infrared coating of the bulb, which put out a light like a 50w. They are more energy efficient in that aspect. My understanding is the IR coating traps the IR light inside the bulb and puts out more of the visible light. Cool but way more expensive. I spent days trying to find the cheapest (range of the IR bulbs were $15-$75). I definitely recommend a soft start dimmer, bulbs last forever. I have the Maestro Dimmers. My mother has mr-16 low voltage on a regular switch and they burn out all the time. Hope this help and hopefully my time I spent on research helps. I'm sort of a light bulb/lighting fanatic.

That is a question best addressed by your local building inspector. If the inspector takes the wording in the NEC literally, then you are out of luck using the sleeve. You should take the data sheet to the inspector & get his/her position clarified before starting work. However, you can use the Romex without using boxes. I haven't heard of any inspectors that require a box to make the transition from low voltage cable to romex.

It is against code to install lighting on counter receptacles, however you intend to install a receptacle and plug lighting into it. It could be OK since it is a receptacle. I'm not sure how many receptacles are permitted under NEC on a counter ciruit.