Perhaps a good place to start is the dictionary and follow up the passages cited? it is an interesting question because Roman attitudes to work (in the sense of paid labour of some kind) were quite different from western contemporary attitudes. See for example Cicero de officiis 1, 42
"XLII. Iam de artificiis et quaestibus, qui liberales habendi, qui sordidi sint, haec fere accepimus. Primum improbantur ii quaestus, qui in odia hominum incurrunt, ut portitorum, ut faeneratorum. Illiberales autem et sordidi quaestus, mercennariorum omnium, quorum operae, non quorum artes emuntur; est enim in illis ipsa merces auctoramentum servitutis. Sordidi etiam putandi, qui mercantur a mercatoribus, quod statim vendant; nihil enim proficiant, nisi admodum mentiantur; nec vero est quicquam turpius vanitate. Opificesque omnes in sordida arte versantur; nec enim quicquam ingenuum habere potest officina. Minimeque artes eae probandae, quae ministrae sunt voluptatum:
Cetárii, lanií, coqui, fartóres, piscatóres, ut ait Terentius; adde huc, si placet, unguentarios, saltatores totumque ludum talarium.
Quibus autem artibus aut prudentia maior inest aut non mediocris utilitas quaeritur, ut medicina, ut architectura, ut doctrina rerum honestarum, eae sunt iis, quorum ordini conveniunt, honestae. Mercatura autem, si tenuis est, sordida putanda est; sin magna et copiosa, multa undique apportans multisque sine vanitate impertiens, non est admodum vituperanda, atque etiam, si satiata quaestu vel contenta potius, ut saepe ex alto in portum, ex ipso portu se in agros possessionesque contulit, videtur iure optimo posse laudari. Omnium autem rerum, ex quibus aliquid acquiritur, nihil est agri cultura melius, nihil uberius, nihil dulcius, nihil homine libero dignius; de qua quoniam in Catone Maiore satis multa diximus, illim assumes, quae ad hunc locum pertinebunt."
(XLII. Now in regard to trades and other means of livelihood, which ones are to be considered becoming to a gentleman and which ones are vulgar, we have been taught, in general, as follows. First, those means of livelihood are rejected as undesirable which incur people’s ill-will, as those of tax-gatherers and usurers. Unbecoming to a gentleman, too, and vulgar are the means of livelihood of all hired workmen whom we pay for mere manual labour, not for artistic skill; for in their case the very wage they receive is a pledge of their slavery. Vulgar we must consider those also who buy from wholesale merchants to retail immediately; for they would get no profits without a great deal of downright lying; and verily, there is no action that is meaner than misrepresentation. And all mechanics are engaged in vulgar trades; for no workshop can have anything liberal about it. Least respectable of all are those trades which cater for sensual pleasures:
“Fishmongers, butchers, cooks, and poulterers, And fishermen, as Terence says.
Add to these, if you please, the perfumers, dancers, and the whole corps de ballet.
But the professions in which either a higher liberal. degree of intelligence is required or from which no small benefit to society is derived—medicine and architecture, for example, and teaching—these are proper for those whose social position they become. Trade, if it is on a small scale, is to be considered vulgar; but if wholesale and on a large scale, importing large quantities from all parts of the world and distributing to many without misrepresentation, it is not to be greatly disparaged. Nay, it even seems to deserve the highest respect, if those who are engaged in it, satiated, or rather, I should say, satisfied with the fortunes they have made, make their way from the port to a country estate, as they have often made it from the sea into port. But of all the occupations by which gain is secured, none is better than agriculture, none more profitable, none more delightful, none more becoming to a freeman. But since I have discussed this quite fully in, my Cato Major, you will find there the material that applies to this point.) Loeb trans. Miller 1913How would a Roman have asked another what they did? It would depend very much I think on the social standing of the participants. I leafed through Eleanor Dickey’s “learning Latin the Ancient Way” but this question doesnt figure in The Colloquia she prints.
In terms of your “huckster” I wouldn’t have thought “officium” was appropriate, nor munus. vocatio also looks wrong as your abbreviation indicates its more fitting to a (christian) religious calling , otherwise it is an invitation. occupatio can mean “A business, employment, occupation (the usual meaning, esp. of public service; cf. studium)” (Lewis and Short) but again doesnt seem appropriate to a “huckster” or inn keeper.
I think you would be safer to think along the lines Who is that man"? “he is an innkeeper”