GEHLER: 1. from "gehl" (gelb) meaning yellow (fair) + "Haar" (hair) / 2. from a place-name Geel / 3. possibly from Gele, a short form of Gertrud (not sure about this)
EHRLICHMANN: Rather "honoured man" than "honest man"
SCHNELLINGER: Most likely from then place-name Schnellingen (in the Black Forest)
SEELER: 1. from "Seil" (rope): maker of ropes 2. from various place-names (Sehlen, Sehlem, Seelen, Sehl)
(most of this is taken from: Rosa und Volker Kohlheim, Das große Vornamenlexikon, Mannheim 2003