Yes this is a "walk-in bath tub." You must open the door, get in, shut the door, and it has a special handle that goes over the door to keep it shut. Then you are ready to fill it up. We have extra large water lines for a fast fill and a tank-less hot water heater so it doesn't run out of hot water. After bathing when your ready to drain, you pull the drain plug(from a upper switch) and hit the "quick drain button." The "Quick Drain" feature is a must, it allows to tub jets to suck the water for the tub so you don't have to wait so long for drainage. These come in "standard" tub sizes 48",54", 60" and more. It it highly recommended to someone who can't get in and out of a conventional tub by themselves anymore.

And so I assume some drain plumbing re=working would be needed. Can this be done in a bathroom on a slab (as opposed to having a crawlspace under it)?

Supply lines and drain line work would have to be done with most any tub/shower replacement. A house built on a concrete slab would require cutting of the slab and exposing plumbing lines to move. I also recommend the water heater to be changed to a tank-less as this tub does require more water than your standard tub.