No to the first. You can still get caught and executed if you try to assassinate a noble in an invading army, as a for instance.
Emigrating is indeed possible. I know of a few infil-heavy families that just trade continents every so often. Plays hell with your H/P, though, and if you go too low you hit outlaw status and can be executed without a ban.
Actually...Emigrating when you have 0 honour increases your H, above the point of outlaw status. Case in point: Iksandros with 0 H emigrated to Colonies from FEI. Gained 6 H upon arrival.
