Yes, with the fault codes, I could tell you what you are looking at to diagnose and repair that, but most likely this will be a different issue from the low compression and burning oil.
For a delaership to do any work, you will be paying more for parts and labor. Labor to do a valve job is 14 hrs, and parts will run about $150.
At average dealer rate of $125 per hour, you would be looking at $1750 in labor, plus the $150 in parts for total of $1900
At average independent shop rate of $80 per hour, same job would run $1120 labor, $150 parts for total of $1270
For engine replacement, at dealer 27 hours- $3375 for short block labor and $3300 for short block, total $6675
Independent shop can drop a complete remanufactured engine for 15hrs labor - $1200, and $3000 for engine - total $4200