Focus is a very good car, the awards speak for themselves. Sounds obvious but main beam on focus is by pulling the indicator stalk forwards, this can accidentally get switched on when flashing. Obviously full beam is only active when headlights are switched on hence you have to drive on sidelights.TBH I suspect stalk switch is most certainly faulty but never overlook obvious. Try switching stalk on/off when headlights on to see if this makes any difference.

For the running issue I would look toward the coil pack, these are notorious for problems causing misfires more so on the earlier models like yours.

Does the door lock if you use the key? I am assuming you are using the remote key if success the lock will need lubricating.

Martin