Can multiple P codes be caused by wrong oil viscosity?

Question

My Story:
I have a 2006 CR-V that I bought last summer; it has about 250,000kms on it.  I checked the oil a couple weeks ago and the oil level was down about 3 (yes, three) litres and the oil was pretty much black.  I knew I had to do a full oil/filter change, but I topped it up with 10w30 that I had on hand instead of the 5w20 that it is supposed to get (because I didn't have any). I know this was a stupid thing to do, but I preferred this option to driving it with one litre of burnt oil.  I thought it would be OK as a temporary fix, as I don't drive the vehicle very much (maybe 250kms/week?). That was a couple weeks ago. Then a few days ago the CEL started doing the 10 flashes whenever I start the car.  This motivated me to do the oil change immediately, so I picked up the oil and filter and took them home. The car sat for a couple days and today I did the oil change (flush, full synthetic oil/filter, and a magnetic drain plug).  

Using my code reader I got the following codes:

P0172 - System too rich - Bank 1
P0300 - Random/Multiple cylinder misfire
P0301 - Cylinder 1 misfire
P0303 - Cylinder 3 misfire
P2646 - Rocker Arm Oil Pressure Switch Circuit Low Voltage

Prior to last week the CEL had never flashed. Using my own reader, I have tried to reset the codes today after the oil change to see if they will reappear, but the code reader keeps showing 'FAIL' and will not erase them. It seems oddly coincidental that these 5 would all appear at once, as I don't recall doing any other stupid things to the car recently.

My Questions:
1) Could using the 10w30 for about 500kms have triggered any/all of these codes?
  1a) If so, will they reset on their own now that the engine is getting the 5w20?
  1b) If not, what else may have caused these codes to appear all at once?
2) What damage may I have caused?
3) Aside from kick myself in the head, what should I do?

Thanks for any help available
Mark