I was flying VFR above a broken/scattered layer with tops at about 9,500 feet after having climbed above the layer. Though I get flight following on 95% of my flights, traffic was so light (due to the pandemic), that I chose not to speak with ATC this day. I knew I had to fly well south of my destination before I could descend in relatively clear conditions. As I was descending and turning to the NW, I was suddenly staring directly at a commercial jet crossing my path from right to left 3+ miles directly ahead and below less than one thousand feet. I initiated a hard turn to the right and shallow climb, and I noticed the jet banking to its right. I was surprised to see a jet in this location at this altitude, so far west of ZZZ.

I fly this route often for training, but rarely above 6,000 feet, so later after landing I studied the ZZZ STARS and saw that this jet was right where it was supposed to be on the STAR. I had collected the weather soon after the traffic encounter and it was reporting 5,500 broken which equates to an MSL ceiling of 7,000, which is about where the jet was. I realize now, that the jet was descending through the cloud layer that I flew around and the jet speed was such that it must have emerged from the cloud layer during my momentary "heads down" to get the frequencies at my destination. The encounter was rattling, and I can imagine the pilots of the jet making a colorful comment or two about general aviators. There are many obvious lessons here. Talk to ATC, maintain a traffic scan and pay closer attention to any traffic information available on the MFD. Nevertheless, I realize now that I do not have a full understanding of the STARs in my area since they are generally used by turbojet aircraft capable of 250 knots and arriving from the flight levels.

I was working all positions combined during the COVID reduced staffing period. Both ZZZ and ZZZ1 were in their north configuration. I had turned Aircraft X to a XXX heading for a vector to the Visual Approach. I had released Aircraft Y on an initial westbound departure heading. During the sequence of events, I had forgotten that Aircraft X was a ZZZ1 arrival, mistaking him as a ZZZ arrival. Both arrivals are vectored in a similar manner to the Visual Approach in this configuration from the north and the Aircraft X call sign made me think ZZZ arrival. The Aircraft Y departure had to build a little altitude before I could turn him north because the temperature was decreasing the climb rate today.

I mistakenly cleared Aircraft X for a Visual Approach to Runway XX and then he corrected me with the "Runway XY" readback. I had planned to go right to Aircraft Y for his turn to the north, but I realized if I didn't correct Aircraft X first, he might turn early towards ZZZ1, so I corrected his heading and altitude first. The lost time, however, resulted in a loss of lateral separation after I turned Aircraft Y to the north. This resulted as a loss of awareness about my aircraft and what they were doing. If I hadn't made the mistake of clearing Aircraft X to the wrong airport in the first place, the sequence would have worked out with enough time to turn Aircraft Y in a timely manner.

About 15 minutes before departure, the flight went nose heavy. I blocked rows 7 and 8 and told the Zone Controller about it. Zone Controller told me he would tell the gate agents to move passengers from 7 and 8. When the flight was finalized it went nose-heavy again. Passengers were physically moved by agents, but not on the computer. The aircraft was showing OUT so I sent my nose-heavy message to the Captain telling him to block rows 7 and 8. His reply to me was I moved passengers out of First Class can we go now? I said, Negative, I need to know how many passengers you moved and where did you seat them. By this time about 35 minutes have passed and he is at the end of the runway waiting.

So now the agents are working on another report to reflect the correct passenger count. But their count won't be correct because they don't know the Captain moved people out of First Class. After all of this, the gate agents re-finalized with a count of XX and YY passengers. Dispatch sends a message to the Captain telling him to move the passengers back to First Class and the new weights are coming. I sent the new weights. Right after I hit the send button the Dispatcher calls and says the Captain isn't moving the passengers back to First Class due to the new COVID seating guidelines. So I invalidated the weights again. I asked the Captain to now send me a report of where everyone was seated. I didn't get a response for a while until he showed airborne. Then he sent me a message stating, 'Too many distractions and threats. We are airborne.' So now we have a flight in the air without correct weights.

During our flight from ZZZ1-ZZZ we were cleared to descend via the ZZZZZ Arrival into ZZZ1. Due to the Coronavirus there was a logistical situation developing at our destination that ultimately resulted in our being stuck at the destination without transportation, and me and the Captain were actively engaged in conversation trying to solve that issue. The bottom of the descent on the ZZZZZ Arrival is 11,000 feet. The aircraft had leveled at 11,000 feet and then a short while later I noticed the vertical path indicator descending indicating we were passing through the descent point for the proper descent path.

Due to being focused on the conversation at hand, I was confused as to the state of the aircraft on the arrival. I had lost situational awareness of the fact the aircraft had already leveled at the bottom of the arrival and assumed we still had more altitude to lose. I questioned the situation asking the PM what the deal was and why we were not descending. The PM was trying to determine the issue and at that point, I initiated a descent. Almost immediately we both realized that the aircraft had been level at the correct and final altitude on the arrival and I immediately initiated a climb back to 11,000 feet, which was our clearance limit. Unfortunately, we had descended to 10,500 feet during the process.

After the fact we realized that the issue happened because the PM had put a crossing altitude at the airport for planning purposes and that was generating the vertical guidance that caught my attention and caused me to get confused. We had not discussed the altitude put in at the airport yet due to the discussion pertaining to the logistics developing at the destination. The issue was completely my fault. I should not have initiated a descent without first confirming the state of the aircraft on the arrival. In an attempt to keep from getting high, I caused us to actually get too low. This is also a good reminder to deal with ground issues on the ground or in downtime during cruise, and not during the arrival or later phases of flight. We were not in sterile cockpit but it was not the right time to be dealing with the logistic problems, at least not the PF!