TH Procing

[Alhanelem]

1) is very testable, it doesn't need a response. Casually though, I don't see any evidence that this happens or see any reason why it would.
2) No. We already know what TH+ does. This is also testable but I don't see that it's necessary, I've never heard anyone say this before and it's most likely either just anecdotal eyeballing or a complete fabrication

Again, you can test all of this, but no claim has ever been made that TH+ on gear modifies the chances of anything happening; it only modifies the TH level on the target, and unless/until someone proves otherwise (like i said, the chance of anything is completely testable) it should be assumed that no change in chances for anything (other than the drop rate chance provided by TH application) occurs.

We also haven't gotten any internal responses to anything in a very, long time, so I wouldn't hold your breath. Sorry to be a debbie downer. But, like I said, you can very much test this yourself, just keep track of how many TH effects you apply and whether they were applied alongside a critical. You just need a large enough sample size.

If it helps, based on this earlier official comment on TH:

Camate Wrote: Adding Treasure Hunter+ via equipment, or other means, will not increase the rate at which the Treasure Hunter value grows, as this is a set rate.

I would lean towards there being nothing modifying the rate at which you can apply TH procs.