The question intonation is there. You can hear a rise in pitch on the next-to-last syllable: Férfiakat ker ES el?. English would end with the pitch rising; Hungarian has an ↗︎↘︎ pitch pattern beginning on the next-to-last syllable. (Except very short one-syllable questions obviously.)
In writing, the only difference between this sentence and the declarative Férfiakat keresel. is the punctuation at the end.
Well, it's at least regularly irregular :)
All (?) verbs with a stem ending in -s -sz -z -dz add -ol/-el instead of -sz: http://www.hungarianreference.com/Verbs/Verbs-Indefinite-Conjugation.aspx#s