In my view, seeking first the Kingdom of Heaven does involve, to a degree, these less important things you've mentioned.
For example, people should first and foremost be concerned about marrying in accordance with the laws of the Church, which means marrying a Catholic. So part of seeking the Kingdom of Heaven involves seeking a Catholic spouse. I think that if you want to get to heaven, having a helpmate who is going to be just that -- a help -- rather than a hindrance is going to be of paramount importance. So not just a Catholic but someone who understands the faith, cares about it, is prepared to submit to her husband (or love his wife), etc. So these are by no means trivial.
Similarly with a job, although I agree we should not be overly concerned with this, when one is young it does bear consideration of what sort of job will be less of a hindrance to one's sanctification. And of course some jobs will be outright impossible for a Catholic to pursue given the compromises and immoral activities that would be required.
i did not say and don't think i implied in any way that those things were not important. But here's something just about everyone seems to overlook concerning those matters (whom to marry, etc):
Few think of this: Why marry anyone? Marriage is difficult after the honeymoon... and sometimes b4. And the Word says it is better not to marry. Jesus of course never married. I have never been married but i have been in love so called many times.. It never worked out. Thank God I found out it wasn't going to work long before it got to the point of marriage much less the possibility of divorce, much less divorce when you have children.
In any case, my point was that if people had it on their mind and heart to do God's will at all times and in all ways, well, you can't go wrong just focusing on getting to Heaven first and foremost. And again, as the psg says, all these other things will be provided.
Few people do that iMO. If they did that, Jesus would not have said that "few" find the narrow way. The saints would not say that very, very few make it to Heaven... People generally do NOT put God's will first