Yes, Pin 2 being "hot" corresponds to the 1/4" tip.
There may be cables that are wired differently. That's why we post the specs on how we wire ours.
For question #2, I'll have a guideline you have to follow. Everytime you have a +4dB line level, the Eventide *MUST* be connected with its XLRs. For instrument signals, *USE* the 1/4". This is how we wire our units. Try keeping the connection balanced as much as you can. If you need to unbalance it, always do so on the other ends of the cables connected to the Eventide, NOT on the ends connected to it. I have no specific answers on your setup as I don't know what kind of signal the TC accepts/sends out…and because it's not something we support.
3) answered above…keep things balanced if you can.
4) I would never connect any digital processor in series with another. Parallel schemes are much, much better. Using a splitter/mixer or a router is the key to better signal to noise ratio, system flexibility and creative routings. Check the technote on gtr rigs….and learn more about this by reading documentation and examples about an amazing device called Switchblade, FYI.
all the best