The coolant hose just to the left of that hole normally goes there. There is a section of metal pipe that bolts to it then the hose connects to it. The hole where your hose is currently is then blocked with a cap.
Some blocks (K24a1/a4/probably others) don't have that hole for the coolant line...
Check out the YouTube channel "Pirate Garage". He has some videos up from earlier this year of AWD converting a K swapped EM2/ES1. EM2/ES1 share the same platform as the DC5 (more or less). I have been wanting to do this for years.
The a3 harness will not have a connector for the reverse lockout. Other than that everything should connect just fine. But if you're going to use the K20a ECU you must use an adapter harness or re-pin your a3 harness to match.
Camshafts are in time with each other. Can you also snap a pic of the crank pulley lined up with the mark on the timing cover?
Also, did you assemble the engine or was it already assembled when you swapped?
You may want to consider checking engine timing with all those crank/cam sensor faults.
Oh I see you already did check timing. You need to verify if it is off a tooth or not. That very well could be the root of all your issues.