Sometimes typos are put into the initial body text of the bug report, or additional comments for that matter. Being able to edit the initial body would be able to fix this problem.
No. It would be really confusing to say at least.
Besides, this is not possible, feature requests for Bugzilla need to be requested UPSTREAM - https://bugzilla.mozilla.org/enter_bug.cgi?product=Bugzilla
*** Bug 115881 has been marked as a duplicate of this bug. ***
*** Bug 129041 has been marked as a duplicate of this bug. ***