Grade 1 is fine, PEI 4 is for light commercial/industrial, so it should be a tough wearing tile. 3% is on the line between vitreous and semi-vitreous, if you really want to get specific I'd consider it an indoor, non-frost tile to stay on the safe side. If you're worried about chips, the bisque body color will show on any glazed tile. If chipping is a strong concern, you might want to look at an unglazed ceramic where the tile is pretty much the same color on the surface as it is throughout the thickness of the tile. Ceramic is hard and unforgiving towards dropped objects, in a kitchen that might be a concern. I put cork on the first floor of my beach house several years ago. It handles bare feet and tracked sand very well. No wear issues, and it's "warmer" than tile. But it depends on what you want and how the house is used.

Unglazed would be my first choice, because it tends to have a slightly higher COF [coefficient of friction: a measure of sliperiness. Higher is better, this number can be found for most tile on most major manufacturer's websites.] Wear is meassured with a PEI number. Most porcelains are rated as 4 or 5, either is acceptible for commercial installation and will last longer than any other material in your home, with the possible exception of granite slab counters. Since unglazed has no coating to wear off, it will generally have a higher rating than glazed BUT there are many of both types rated at PEI 5, meaning they'd stand up to mall or airport use, with thousands of people walking on them every day. Unglazed [aka, 'color through', color body', 'solid body', 'through body'] has the pigments evenly distributed throughout the tile [though the face still tends to be darker]. That means any chips [pretty rare with porcelain] are self-disguising. A lot of people hear 'unglazed' and assume the tile will be porous enough to absorb stains. It isn't: a modern porcelain is so non-porous that everything sits right on top and washes off easily. The only maintenence issue then, is grout. GO DARK. As dark as you can possibly stand.

I have black and white 12" tiles and black grout like Elizabeth, but mine are straight to feel right in our old farmhouse. The kitchen entrance is used almost exclusively, so the tile handles the grit, snow, and mud that comes in from the gravel drive without any issue. We have in-floor radiant heat, so it is toasty warm in winter and cool in summer. I've lived with this floor for 17 years, and the floor in my previous house was tile as well. It wears well (I am not into renovation for the sake of newness), cleans easily, and looks as good as the day we installed it. Ours has a bit of a gritty texture that prevents it being slick if it's wet, and I think I've only broken 2 items in 30+ years in the two tiled kitchens. I don't find it is hard on my body, but I usually wear supportive shoes when I cook since I don't want to worry about burns or injury from dropped items when I am cooking.

I would get myself over to Yelp, and research local flooring stores that sell product AND do installation. Read through all the reviews. Get a comfort level that you can work with the folks in the store, and that they stand behind their products and work. Even more important when you're doing the whole house--it's a big project! When things go wrong, and you can read through many, many threads about that, the manufacturer points at the installation, and the installer points at the manufacturer. It is an uphill battle, it can get $$$legal$$$, and when I put flooring in our whole downstairs, I was (rarely for me) less concerned about saving $1/sf than I was concerned about not having anything go wrong, and in the event something did go wrong, having a long-standing store with LEVERAGE over the manufacturer to reduce my risk. I'm glad I went the way I did, and after all my questions, I went with the decades-old family-run store with the great reputation across town. They made great recommendations, and made sure to offer me all my options/upgrades up front, and didn't try to talk me out of anything that was important to me: (e.g. I asked for no quarter round to have a sleeker look of baseboard meeting flooring). Be sure to ask about additional costs for moving furniture, and which crew they will send. In my case, they sent their "best" crew (most experienced), and I agreed to wait for them. They picture-framed our hearth (mitered corners-looks great), and "beefed-up" a stair step that leads to our front door, making it wider/safer--at no extra charge. There are things that a homeowner might not know about (cheap glue?), moisture issues if you're on a slab, etc. These are just my thoughts and experience. You can also read through a lot of threads in this flooring forum to see what goes wrong for folks, and get a better idea of what questions to ask. Good luck!