1) the jailbreak is effective as it pokes at an exploit in the ps3's SYSCON initial configuration check.
swapping a hard drive may not delete all traces of jailbreak from your system - imo, its very unlikely it will delete all traces, but id still advise on doing it, in case anything at all can be removed this way.

2)@FinalMix: every time you start up the ps3, it must be a cold boot and the n900 must be plugged in; you MUST do the power/eject button combination. this unloads the enabling script. unless this script is run, the ps3 is not running in dev mode.

also, no, you must either leave your ps3 always on, or always cold boot it when you want the jailbreak, for the time being - it is possible in the future you can boot from standby to the jailbreak.