Joe, I've been using one as a planetary and guide cam for almost 3 years, works like a charm. The 224 is very sensitive.
Earlier this year I bought a 290MM and that probably has a slight edge from a guide cam point of view, but it's not by a lot. And it's not like it's improved my guiding
Couldn't tell you about Linux...check ZWO support forum. IIRC they do push out their SDK regularly, so it's entirely possible.