IIRC, the neutron branching fraction for the proton-boron reaction is around 1%. So it is not clean, but the flux is low enough not to do much damage to the walls of the fusion chamber.
True. It would need a bit of shielding. Some of the picosecond laser papers say the total radioactivity per megawatt would be less than what's released by burning coal, which contains a little thorium and uranium. Here's an abstract that mentions that:
http://www.davidpublishing.com/journals_show_abstract.html?7...
(Google will turn up plenty of full papers though.)
If one of the boron fusion projects works out, we won't even have the neutron flux.