On your question about inferring threshold, I think the advice would be to re-do the test as per this article: https://uphillathlete.com/heart-rate-drift/. “Reading and Implementing Your Results…>5 percent: Your initial heart rate/pace was above AeT. Redo the test using a lower starting heart rate. It may take several attempts to nail a decoupling that is slightly less than or equal to 5 percent”.
I tried to post some links to TP articles answering your questions but seems the post did not upload so I’ll copy pasta from TP.
TSS: “You earn 100 TSS for an all out, 100%, 60-minute workout. Of course most workouts are not completed at 100%, so most workouts will accumulate less than 100 TSS per hour. You can earn more than 100 TSS within a single workout (as long as it is longer than an hour), but never more than 100 TSS per hour”
IF: “Intensity Factor is the ratio of an athlete’s Normalized Power/Pace to their Functional Threshold Power (FTP)/Pace. In effect, IF is the fraction of an athlete’s threshold they maintained for a workout or parts of a workout…For TrainingPeaks to calculate an IF for your workout…You need a power meter”