padded undersuits

Somewhat suprisingly, I could find almost no information in the memories regarding padded 'muscle' suits for wearing under a fursuit. Therefore, I have a bunch of questions about them.

1) Are they comfortable? Aside from looking quite hot to wear, can you run/sit/bend over/etc?

1.5) How do you get into the undersuit? Zipper? Spandex?

2) Has anyone made a muscle suit for a feral costume? Digitigrade legs, barrel chest, thick neck. That sort of thing.

2.5) How do you make a costume with a thick neck yet still have a removable head.

3) What would be good materials to use? Stiff/soft/etc? Solid foam seems like it would be quite hot.

4) How to tailor the suit to 'show off' the padding underneath? Adding ab muscles is all well and good, but the fur overtop will just slide over the 'muscles' without defining them.

5) Is it better to just have the over and undersuits permenetly attached?