In SeaMonkey and Firefox you can change the behavior of the backspace key with the pref browser.backspace_action (in the pref editor under the URL about:config). The value 0 means (Shift+)backspace goes Back/Forward, 1 means act like PgUp/PgDown and 2 and other values make the backspace key do nothing.

As long as they they include all fixes the Mozilla Foundation does, why not? The 1.0.3 and 1.0.4 were also only Security releases, i don't think many non security-fixes went into it (but one can check if he wants).