Code P0304 - replace ignition coil

My 2010 4 with 174k started acting up a week ago with a sporadic mild to moderate shutter whenever I would gently accelerate - then if I ease up and accelerate quickly the shudder would disappear.

Day by day the shuddering frequency increased, today the check engine light appeared so I went to the Autozone and extracted code P0304 - replace ignition coil on cylinder 4. Spark plugs were replaced at 150k.

My questions are:
1. Do I have to buy genuine or can I go generic? Genuine costs $75 per, I can buy a generic 4pk for the same amount.

2. Should I replace all 4 ignition coils at the same time? If I have to remove all the wiper stuff I might as well replace them all if they are still all original.