What next?

[flouese]

Changed my oil, started up the car (99 base) and the CEL is shinning brightly (not flashing). I have no history on the car and it has 165k miles. I paid $5k for it knowing I would have to put some money into it.

Pull out my reader and got the following codes:
- P0130 O2 sensor ahead of the catalytic converter (cyl 1-3) Intercore short circuit or limited
- P0150 O2 sensor ahead of the catalytic converter (cyl 4-6) Intercore short circuit or limited
- P0305, 0305 & 0306 misfire cyl 4-6 Damaging catalytic converter
- P0506 Idle air control -idle speed too low (note been idling at between 1000-1200 rpm)
- P1316, 1317, 1318 Misfire Cyl 4-6 Emission relevant
- P1319 misfire, emission relevant

Not code related, I discovered during the oil change that there is a coolant leak from the top of a hose on the right rear of the vehicle.

What is the most pressing that need immediate attention? Where do I start and which is the most economical issue to start with. Too many other house projects in progress and I don't want to break the bank.

HELP! Any direction and assistance will be appreciated. Don't want the wife to see the car as a paperweight taking up space in my driveway.