They are suitable for either.

They are metalic red, from certain angles they do look a little pinkish.

Unfortunately this skewer will not fit 140mm axles.

Use mine on 700c wheels - if that answers your question

Not sure if you'll consider this an answer or not.
I don't ride or like MTB I prefer road bikes and I was worried about whether the rear skewer would be long enough when I saw them. My bike(s) are a Scott CR1 with a 10 speed shimano ultegra cassette and a Carrera Vanquish with a 9 speed Shimano Tiagra cassette. Both bikes the rear skewer has fitted perfectly. The end of the skewer doesn't protrude so I didn't need to shorten them at all. I'm not sure if I'd describe these as 100% secure skewers as the hex head is a standard size with nothing special about it, I used a cheap bike multitool to do it up. So a thief could undo your wheels with a cheap tool and a bit of time, the important bit is the extra time reqd rather than just flipping a QR paddle. but for the money they are good skewers.

Approx 80g per pair.

Yes should be fine.

Cycleops trainers use their own quick release, which comes with the trainer.

Yes these skewers will fit a SRAM 406 wheelset.