Hello :) Im only a "binhi" (younger than 18) so Im not sure if what my answer to your question is correct but yes, "mangagawa" are allowed to "hiling" the inc girl they like, but not for marraige, but to simply court her first. The girl can of course, allow him or regect.
If she does allow it, through time, when their relationship grows, the "mangagawa" can "hiling" to marry the girl.
I think they only have that privelage once they're at their peak(?) or they're near to becoming an INC minister.
Even if they've already finished their studies/training and become a full pledge INC Minister.
But if an INC Minister has no wife for so long and he doen't have any one in mind (a girl he wants to marry) the other older ministers will help him find one, and set them up or something.
Im from Philippines, english is only my second language. And Im still learning the english terms of titles/names in INC :)
I hope you find my answer useful ^^