E6

I'm about to start processing E6 with the Tetenal kit. Is the process as straightforward as C41?

More steps, longer process, but the same basics apply; keep the temperatures with water bath. So yes, it's straigthforward if you've done C-41.

Temperature in first developer +/- 0.3 degC, temperature before and in Color Developer (including the wash after FD) +/- 1 degC, after that it's not critical at all.