Cadillac Repair: Codes Failed Emissions, threshold bank, driver 1

Question
My car is a 1997 Concourse Deville, it failed emissions because of Code P1645 and it reads Driver 1 - Line 5; what exactly is this and what can I do tohave it repaired?

The second code reads P0420:  Catalyst below threshold (Bank 1); however I took it to the muffler place and they stated nothing is wrong with my catalyst converter - please advise..


Third Code:  P0441 - Evap. emission control incorrect purge flow; what will correct this problem?

P0J02 is the 4th Code:  Cylinder 2 misfire, what does this mean?

Answer
IS or HAS the CHECK ENGINE light ever illuminated while driving the vehicle and or has any other lights illuminated or any messages from the message display center ?.

What work or diagnostics of ANYKIND WHAT-SO-EVER have been performed on the vehicle trying to fix this problem ?.