Fuzzfizz:

"Toggling between two  presets in a single preset" confuses me a bit – does that mean two reverb presets in a single algorithm, or just change a parameter in a preset. Can I go from a long hall reverb to a short spring or room?

It means changing preset parameter values in a single algorithm.  The functionality is explained in the H9 Control user guide in the "Programming the HotSwitch Patch" section.

http://eventide.com/AudioDivision/Products/StompBoxes/H9ControlUG1.aspx

Toggling the repeat, just means turning on and off the repeats? Is that pretty much the same as turning off the delay ? Seems no repeats = no delay, so just like hitting the bypass or off button on the pedal?

Some things are easier to see than to explain; check out this video:  https://www.youtube.com/watch?v=cnH828Wsldc

Fuzzfizz:

Also, do they make a switch that has three buttons plus an expression pedal? Or would the expression pedal have to be midi?

You can use an expression pedal with a single button aux switch using a y cable; this pdf explains how: http://www.eventide.com/~/media/Files/Audio%20Support/H9/Everyone/H9_Y_lead.ashx

Some users have had trouble getting this to work with various expression pedals. So, if you want to do this, I'd definitely try it with one of the products that we've tested and were mentioned in the pdf.