You have some nice E-6 films. Why not help keep E-6 labs alive and E-6 chemicals produced by processing them as intended? If you want bad b/w results (by traditional criteria), try weird cross processes...but if you want good b/w results (by traditional criteria), use b/w film. It is cheap...and good!
As for the exposure thing when cross processing, IME, color negative film (being a low-contrast medium processed in chemicals designed for an inherently high-contrast medium) loses a ton of contrast and density when shot normally and done in E-6 chems. Thus, I overexpose about two stops when I do this, and usually push one or two. Going the other way around, C-41 chems on E-6 film jack up the contrast. (You are putting an inherently high-contrast film into chemicals that are designed to work with inherently low-contrast films.) The shadows get dropped like mad, and it is easy to lose the high tones, so you don't want to push unless you want contrast that is off the charts. I overexpose E-6 films for cross processing by two stops unless I want totally empty shadows. IME, and in a brief test I did with a MacBeth chart and grey card using EPN and Astia, this gives far less contrast when printing to make middle grey the same as the shot with normal exposure. It changed the six-square grey scale on the chart from about four discernible tones to all six being [barely] discernible. Astia was even lower in contrast, but harder (if not impossible) to get anywhere near standard color, so not a good choice when you want the cross processing effect to be subtle. I don't know, but my guess is that this is due to the extra color later on Fuji films. The films come out tinted heavily green, and prints come out tinted heavily magenta. EPN, on the other hand, was very close to standard color, with just a little bit of a "tweak".
