Yep - one of those questions that usually comes with a TMI warning.

The normal way to tell is the stretch test. Have a look on the fertility friend website, there should be some info there.

Generally, I now wait until EWCM before DTD so there is no confusion.

Semen is usually stringier and doesn't stretch as far. EWCM should stretch over an inch, over and over and over again, whereas semen breaks after a few stretches.

Not sure on how long it stays - up to 5 days?