Now, if we explain issues we encounter in a succinct and CALM manner Bethesda will respect that and likely take action sooner. So let's get started posting our quest bugs or seconding ones already posted.
I played for 20 hours before my first bug and it was on the companions quest. I accepted Kodlak's mission to kill the witches for their heads. I went off and played about 3 hours before actually killing them, and now no matter how I handle the witches the quest line breaks. That is, when I return to Jarvaskrr, the Silver Hand has attacked and Kodlak is dead. After Vilkas chastises me he just goes back to his normal behavior. I have tested this many ways including loading very old saves and finishing the quest, dismissing Lydia, eradicating the witches, not eradicating them. You get the idea.
Now it's your turn to second or post new bugs, please. If we act politely (no matter how upsetting this is) things WILL get done.

anyhoo say i come across bugs that prevent continuation of quest, if said bug is patched could i simply carry on the quest or would i have to start a new game for the patch to take effect?
guess the best thing to do is make a save before you attempt the quest so any problems you can revert back and note the quest down to avoid until patch.