On your first point, my answer is yes. My advice is to always avoid faux bolding when possible. When I load your paper in Mac Firefox, I find the headings and particularly the title distracting. The registered trademark glyph looks more like an icon trying to say “No capital P allowed.”
I’m definitely not in favor of using faux bold and italic as a way of saving bandwidth. If bandwidth is a concern then I think it’s more appropriate to use a web safe font and avoid downloading the web font entirely.
On your second point you are correct. The same weight of font will be used for both normal and bold. So my duplicate font face trick is really only appropriate for web fonts used in headings, where you want to preserve bolding behavior in fallback fonts. The other option in comment 6 might be a good alternative for google fonts, I have not tested it out.
On your third point, you are probably correct that the duplicate font face will not work with IE8. If your test confirms this please let us know.