Sure, you could bunch it all together, but since it's speaker cable, I'm not sure why you would want the hassle of pulling it all through tech flex..
For the 4 channel, I'd guess that you could get it all in around 7/8 diameter tech flex. To be on the safe side, maybe inch...
For the wall to towers? 3/8 inch should be plenty. I suppose that for the WAF this one might make sense....A dressed up look since they are visible.
If you don't see the wire from receiver to the wall, just use velcro wraps to keep them neat...