I have found the answer to question #1 myself - YES!
For a bit of added context, I have a Kawai RX2 in the living room, and an ES8 that has been gathering dust since I got the RX2.
I hooked up the ES8 as a midi controller and found that the normal touch curve was just too heavy - even whacking the key way harder than I ever would, it registered 124 max. I changed it to light and it's quite a bit better - a reasonably hard strike tops out at 126. That might actually be good from a programming standpoint, as it means I can program instruments to do something special at 127 and edit the velocity manually when I need it.
Anyway, that experience is what led me to wonder about how different devices program velocity curves.
The VPC1 is in the lead because MIDI control is its raison d'être and is programmable in ways that I would appreciate. It also means it's a lot easier to find things in the manual - it's devoted to programming the controller, so I don't have to wade through all kinds of other features I'm not interested in. I did notice that the pedals are programmable for CC #, and the VPC1 supports 5 presets on board, which I would find useful.
The VP11SE is under consideration because it has pitch bend + mod wheel, possibly better action (clearly subjective, people disagree on this), and on-board sounds that I would use.
PHA-50 boards are under consideration primarily for ergonomics reasons. I have a monitor arm that I use to float an iMac above the keyboard. The Kawais, at a bit higher than 7" tall, would put the monitor a bit higher than I'm comfortable with (and in fact I would need to change my setup, as the monitor arm won't even go 7" higher than the board, resulting in some undesirable pressure between the iMac and keyboard case). A PHA-50 board would not have that problem. My experience playing PHA-50 is that it has better action than the ES8 - but I'd need to play them side-by-side to know that it's worth the added cost.
One thing I'm experimenting with is placing the iMac in front of the fall board, right above the keys (pictured below). That puts the screen a bit closer to me than I would like, but seems to be okay if I turn the brightness down. And I can compromise and push the keyboard back an inch or so, which is farther than I would like, but, compromise.
I believe I am reasoning my way into a VPC1, subject to it being comfortable in my setup - which I can at least experiment with the ES8 for a few weeks to see how that goes. I am still interested in people's experience with programming the velocity curves of the MP11SE and PHA-50 boards.