It's quite a complex issue. The story is a harem at its core considering the main theme of harems, which is feelings of love. You can split girls in this series into three categories.

But, before I dive into them, here's a tl;dr: No, the women that will end up romantically involved with the MC won't be doing any sex-related things. The MC might have some casual, mutual fun with some different characters but they aren't meant to be his "lovers". More details below.

First, the MC lovers - along the way of the story some characters will develop or announce their feelings towards the MC and may end up in a romantic relationship with him. Even if they somehow help with the brothel, it would most likely not be connected with any sex-related thing. They can be totally not linked with the establishment, like say for example travelling adventurers. Purely hypothetically, one of them could end up with the MC and not join the brothel.

Second, women who will have literally nothing to do with sex - be it servants, cooks, maids, guards or any other positions that are required in a working environment. They might be characters somehow saved by the MC and ending up helping him with the establishment, without any sexual services, and also they do not have to end up having sex with him either.

Third, girls that the MC will either employ as prostitutes or they agree to work as ones after being saved by him and maybe offered shelter or something. The latter part will most likely undergo "training" with the MC teaching them what he knows about lewd things. Saying that, prostitution will not be described. Only acts containing MC and potential girls. Also, the story unrolls slowly, so while at the start most of the girls might be slaves, it won't stay like that for long.

I tried speaking theoretically as much as possible to avoid spoilers. One more thing, the brothel won't be some kind of lousy establishment, it kinda is a spoiler, but it will be a high-end one with access granted only after MC makes sure the clients won't be bad.

Most of the girls that will end up working with their bodies will most likely enter relationships that usually base on mutual pleasure (eg. some races might just be horny), fun, gratitude, subservience (some races might just like being under someone), and I guess many other kinds of feelings that don't exactly revolve around pure mutual love relationship like girlfriend/boyfriend, husband/wife, groom/bride, etc. 

And as for how many, that's really hard to pinpoint. I can't say that once I'll introduce a girl like that, then again the lover one, then the working one, and give a pattern like this or something because this all depends on the flow of the story and I'm mostly focusing on how it feels and not just to throw more girls faster to the pot of lewds. 

For example, there might be also cases where more than one girl of a certain race (let's pick Elves here) arrive at the brothel, let's say 3. One of them might end up falling for the MC while others may actually agree on working later into the story since they don't really feel attached to the MC, but enjoy the physical contact with him and don't mind helping with work if he'll still embrace them. The first one will naturally stay only with MC as she decided, for whatever reasons. In a situation like this, most of the screentime will be given to the first one naturally, with the others appearing rarely when it comes to sex. Maybe some big elf orgy or something.

As stated everywhere I can, I'm heavily against NTR, cheating and such stuff, so I'm doing my best to avoid creating any feeling that could be associated with any of the bad stuff, leaving only the good vibes in the series. Sharing is quite a sensitive subject, but well, my whole story is a fucking sensitive subject with the whole brothel and all, and there might be some characters that don't view sex as something sacred and just like to enjoy the physical pleasure without much bonding. But even those characters won't be just sex crazy maniacs that don't care about other people's feelings and jumping on every dick around them while their previous partners get devastated when they get to know about this. They'll have morals. Like, informing someone about their way of life before engaging with them in any act or asking if they are fine with that or backing off if they are not. Sex without deeper meaning and feelings is a thing.