Help: Transmission & misfire issues return

Over the last year, the spark plugs, connectors, and MAF were changed. Always put the best petrol in the car. Also had the transmission fluid changed. All in all, the car has been a pleasure to drive.

Now the transmission is not shifting properly, it hesitates to upshift properly. Sometimes when it changes from 2nd to 3rd, there is a moment in between when the RPMs increase dramatically as if I had shifted into neutral. After a brief moment, the transmission engages at the higher gear but with a hard slam within the transmission, causing the car to shake a bit. Sometimes there is even a horrible sounding streak that sounds like a tire slipping on wet pavement.

4th and 5th gears sometimes have issues, but it's much worse with 2nd and 3rd.

These problems occur almost everytime I drive her. Sometimes the problems do not appear for 15 minutes, other times they occur right away.

Of course the check engine light comes on. I track the codes and erase them each time. Here are the codes from the last ten times:

16684 10 times out 10
16685 7 of 10
16686 5 of 10
16687 2 of 10
16688 10 of 10
16689 10 of 10
16690 4 of 10
16691 10 of 10
16692 7 of 10

All of these are misfire codes.

Additionally, once I got the following set of codes. This particular time the transmission went into fail safe mode.

18112, kickdown
17140, shift Solenoid B Performance or Stuck Off

Questions for those more knowledgable than me:

1. The transmission is what is affected, so why all the misfire codes? Are the misfires confusing the transmission?
2. What about solenoid B? Could the problem simply be debris blocking the opening and closing of the solenoid?
3. Anything else I should consider?

Thanks for your help.