It sounds like you have already nailed the First of Larry Wall's Three Great Virtues of a Programmer (i.e. Laziness, for the truly lazy the other two are Impatience and Hubris - give yourself a a pat on the back for not bothering to look them up).
Impatience should require the use of Off the Shelf parts - possibly an ideal opportunity to buy a Raspberry Pi if/when they ever become available.
As for Hubris, I'd suggest giving the Mk2 it's own web interface, plus real-time webcam feed.
However, going back to Laziness for a minute. I don;' feel that having the device controllable from a phone or PC quite does it, for the truly lazy. Surely the object of complete laziness is for the device to do everything itself? Possibly up to and including re-ordering it's own SLA batteries when it detects the current ones are failing (shades of 2010 A Space Odyssey:, perhaps? Just keep it away from hard vacuum.).
One final point on the topic of a cylindrical cutter. Check out the blades that woodworkers use in planer/thicknessers. Apart from being scary sharp, really: SCARY sharp, they could be the sort of thing you'd be looking for. With a few adaptations, the Mk2 might even keep your hedges in trim.