Shame you don't scan the gauges frequently when driving as knowing if all at once or sequentially would be useful info. Try swapping the gauges on the other plugs to see it that helps. That'll tell you if gauge, or medallion, or sensor.
Heaps of info on themalibucrew. Also Ron Tanis has these useful history and testing videos. Your version of course doesn't have the pitot air tubes.
Effort to replace with TRD kit is minimal. Certainly less than 2hrs. If in a hurry could be 30 mins. Only you can decide if repairing, replacing stepper motors, replacing gauges, upgrading to TRD etc is worth your time and money or if you take risk and rely on alarms preventing engine damage. Personally I'd not be comfortable without oil pressure.
Fuel level fixes are known and common to most boats (replace wire, better earth, replace level transducer). They're just a bit of a hassle to do.