1. Badspot chose to use the older version rather than the newer one. I don't exactly remember why, but maybe the newer engine was either glitchy or couldn't support some of the stuff he wanted in the game or something, so he modded the older version himself to his liking to use for Blockland. $20 is fine. Hell, I'd pay way more. Also, bricks are limited in the demo because it's a demo, lol. And this isn't Badspot's only job, IIRC he works at Garagegames in Oregon.
2. What the hell? How else would you place blocks? What do you have in mind? I honestly see no other way of placing the bricks. The reason it's Enter on the numpad is because it's close to the brick movement and rotation controls. (Incase you didn't know, the rest of the buttons on the numpad control the brick aswell. You don't just shoot the ghostbrick and hit Enter all the time, which may be what you're doing.)
3. Can't really happen with the way bricks are rendered, IIRC. The bricks in this game aren't .dts shapes anymore, which saves tons of lag, but also means they can't be stretched, moved, or rotated more than 90 degrees after being placed. I suppose you could have them turn into .dts shapes after you blow them up or destroy them, but that's really freaking gay and nobody wants that. It would also bring the lag back. Player ragdoll would be nice, though. Limbs flailing when flying through the air (dead of course), or when you die by slamming into a wall you bounce off or just plain break apart. This is a good idea, may be hard to script.
In closing, no, and, yay Facepunch!