Can someone tell me where to read more about Soontir Fel, howlrunner and other eu pilots? Which books have which pilots?

Thanks!

Wookieepedia has all of your answers and links to their sources.

Sadly most of the pilots are just back ground extras that an old star wars card game put names to so they could make more cards. For Fel, look for the old X-Wing Rogue squadron comics. He shows up about about mid way through the series and has one comic that all about how he joined the Empire and became a TIE Pilot and got command of the 181st. Fel doesn't show up too often in the books though.

The X-Wing novels though are pretty good and follows Rogue Squadron and later on Wraith Squadron. They have some overlap into the Imperial side as well, but not nearly enough.