1. No, you don't *need* a light rail. I would, however, question why you don't want UC lighting as the task lighting is amazing!

I think you've seen my cabs. Mine were built without putting a separate light rail attachment. The bottom of my uppers are plain and straight. Even though they do conceal the UC light bars, they appear as if they don't. I think it looks great. Make sure you specify your wants to your cab person. Make sure you have 18" (or a little less if you're OK wiit less than standard) clearance between uppers and counter.

2. Toe kicks are a personal chocie. I do stand with my toes in that space sometimes during prep depending on the task. Do you currently have a toe kick? I'd suggest blocking it off somehow and see if it bothered you. Alternatively, occasionally during meal prep look down for a toe check. Are you toes under the cab?

I think kitchens without toe kicks look interesting, but wouldn't be functional for me. I'm all about function and what makes preparing a healthy meal from scratch the easiest on me, the sole cook and bottle washer. Bumping my toes on a cab and not being able to stand where I like would irk the stuffing out of me. YMMV.

I think the answer to your light rail question is "it depends". If you are doing frameless, unless your door front matches your cabinet interior exactly, you will probably want them because the bottom of the cabinet will match the interior and be highly visible without a light rail. Some face frame cabinets already have a slight lip on the bottom which hides the bottom of the cabinet, so it might not be necessary in that case.

What kind of cabinets are you doing? White doors with a white interior might be a combination that does not need light rail.

We don't have any under cabinet lighting, but still went with light rail because it just gives the cabinets a more finished appearance and we didn't want the melamine to be so easily visible. Also, if we decide we need lights later, we are ready to go without any major work.

I'm not sure about your toe kick question, but one thing I do know is that islands with legs instead of toe kicks are much, much more money.

Molding finishes off the look of a kitchen, IMHO. Unless you are doing a very modern kitchen that would not look appropriate with molding, and even then, I'd do the recessed bottom that Breezy suggested above. Under cabinet lighting is a MUST if you want light on your work surface. It's the best and easiest way to get that light there. If you are relying on recessed lighting for that, it can be problematic to design it's location that will light that work surface, not interfere with the doors opening or the extension of the molding, and not be behind your head so as to cast shadows. Under cabinet lighting works without all of those issues, as an addition to properly done can lights.

You don't have to do toekick if you can work without it, but you do have to do something there like an ogee baseboard, etc. Molding in that area tends to get scuffed, even if you don't actually ever stand with your toes under the cabinet in the toekick area. Your toes will scuff the area, and that will happen thousands of times over the life of the kitchen. It's just easier to do a recessed toekick to deal with that. For an island, I personally prefer to recess the toe all the way around and then add some decorative feet at the corners to make it appear to be resting on those feet. But, it's really resting on the toe area, and is attached to the subfloor through that area.

I only have two upper cabinets around the sink with a window (and lighting) above the sink. Plus, neither area under the cabs is a working one. The one to the right is not very accessible, so it has a dish rack and also "holds" dirty dishes waiting to be washed.

I use the one to the left for the food processor but I always place the food processor in front of the cabinet as I cannot run it being under it, so no need for lighting either. Plus, the window (and the light fixture at night) provide enough light.

The cabs will be frameless and, of course, I did not think about the cabinet bottom being exposed. :-(

I was totally clueless about cabinet design till just a few days ago, so I am just learning. :-)

I guess I'll allow for a toe kick and just have simulated "legs" like many newer designs do.

Thank you so much for steering me in the right direction!

Eleena, some people have lowered their toe kick height to 3.5" as a compromise.