Re: abs, I have the same problem that most ab exercises engage the neck. But while researching health and fitness, I read an interesting tidbit somewhere about how the innermost layer of abdominals aren't actually activated in sit ups or crunches, and they are considered important for bracing the internal organs and preventing hernias. It clicked with me because sometimes you'll hear about ripped guys like The Rock getting hernias and you wonder why their 8-pack isn't preventing that.

IIRC I read about this in the "Posture: Get It Straight" book and possibly also in Julie Bookspan's book on pain.

The exercise I do for these transverse abdominals is to stand up and forcefully exhale while sucking in my stomach both inward and slightly upward, similar to what you do when squeezing into a tight pair of pants. I find my hips tuck forward when I do this and sometimes I'll squeeze the glutes as well. I do about 5 - 10 reps.

I often hold at the end of a rep, both to increase the difficulty but also to avoid hyperventilating.

Unlike most ab exercises, there is no deliberate raising or hold up of the head. You could of course engage your scalenes during intense breathing, so you want to be mindful of keeping your neck relaxed.

This is all from the books. I have not hit the link above to see what the interwebs has to say in detail. Though I did look at the search results listing and saw pages like "The abs you're forgetting in your workout - Transverse abdominis"

Oh man, I wish I got an immediate onset. I get a delayed onset by days or weeks as the muscles gains size and tension. Bleck.