Girls and boys – did they both go together?

Hello Rabbi.
I am a student at the Yeshivah Da’tal (the same one where you started your journey, by the way). With the opening of the inter-time period the other day, a doubt that has been bothering me for a long time resurfaced: What should relationships be like for girls of the opposite sex? I will divide my question into several parts:
A. Is there even a place for a relationship with girls? Is there a place for dividing between different stages of life (whether mine or theirs)? It’s clear to me that a total disconnect is not a particularly good option, and a complete breakup is probably problematic too; but what about a deep emotional connection, with strict adherence to halakhic boundaries of course (assuming they don’t include anything that contradicts such a relationship)?
on. With some of them, my connection revolves around Torah study. With one I have been studying Daf Yomi for over three years (she is a true Torah scholar, and the best friend I have, by a long shot, including friends from the yeshiva), and with another I study Kedushin at a slower pace. Is this problematic from a halakhic perspective, or otherwise? Or perhaps it is more justified than just a ‘mere connection’? [The friendships are by phone, so there is no concern for exclusivity, etc.; I am mainly concerned about a problematic convergence of opinions.]
And perhaps we should distinguish between studying Kedushin and studying Yerushalmi Damai or the laws of the false Mokudashin, for example?
C. At the beginning of winter, someone approached me and said she liked me. I gently explained to her that I was not interested; but the incident made me wonder about a relationship in principle. It is clear to me that marriage is irrelevant (not in terms of maturity or anything like that, just practical, if I am going to sign a ketubah I should have some way of supporting my wife) for at least the next two years – does it make sense to enter into a relationship knowing that it will have to wait such a long time? Maybe it is better to just wait with this whole thing until a later stage? (Assuming there is someone relevant and we have mutual feelings)
 
There may not be a clear halachic ruling, and in such a situation I would be happy to hear your personal and principled opinion. Thank you very much in advance.