GA pilot reported landing on a closed runway at PAE airport.

Narrative

Arrived at PAE with the intention of conduction 3 takeoffs and landings to regain night currency. I forgot my iPad for monitoring traffic but figured Tower would keep separation; and the pattern would be sparse. Well; when I checked the weather I realized Tower closed; and there were multiple aircraft practicing in the pattern. Backup ADS-B source was not receiving data. The first incident occurred when an aircraft was inbound from the east for Runway 34L; which is a non-standard entry. Nominal would be a straight-in for jets or left pattern for props; but this pilot did a right base-to-final. Also used the identifier 'XXXXX'; which I couldn't pinpoint; so I inquired on frequency; but the pilot didn't answer. The pilot called right base when I was on left base; I notified I didn't have him in sight; so he restated his position and I saw the aircraft's landing lights. I communicated that I would give way and fall in behind. Still thought this was a small GA plane. On final I was aiming for the numbers and encountered some turbulence; not too strong; but surprising for such a calm; clear night. After my full stop landing I looked over and saw the jet taxiing. Everything made sense - call sign; bright landing lights; wake turbulence on final. That could have ended a lot differently.Second incident on the same flight: I intended to conduct 2 landings on the big Runway 34L then my final landing on the short Runway 34R for practice. While in the pattern for 34L I heard an aircraft in the pattern for 34R then he said he was going around; no reason given. After my second landing; there was a commercial jet inbound for 34L so I switched my pattern to 34R as planned. On downwind I could make out the taxiway lights but not runway lights. This is pretty normal. Turning final I could still see taxiway lights but no runway lights - just a black hole. I inquired with the other aircraft on frequency 'Did you have runway lights?' to which he replied 'No; that's why I went around.' Would have been nice to know. So I switched back to 34L and landed.I called Airport Operations and informed them the runway lights were off for Runway 34R; and they responded that the runway was closed when Tower is closed. Sure enough; it's buried in the chart supplement. The abbreviations used in the Chart Supplement; as well as the hours that change with daylight savings time; make it very difficult to gather pertinent information about Runway closures and other safety items. This should be reviewed. Another contributing factor was that the taxiway lights were left on. The led me to believe that that half of the airport; including the runway; would be open. Should all lights in the area of the closed runway be turned off to indicate closure?