Re: Sensing energy from far away: is this achievable or BS?
I don't know whether in theory it's possible or not to read that kind of stuff from body language, etc. I suspect not reliably but I don't really know. Maybe some people can tell some of the time?
BUT either way, the way you're describing your sempai and what he's saying and when, it sounds a lot like showing off. Even if he could tell, to talk about it all the time for no reason sounds silly, like showing off. And to ask someone a question and AFTER they answer to say 'actually, I already knew that' is not so impressive. (And if he only asks it of women and not of men, well...)
Everyone has some faults, though. If he has good skills and is basically a decent guy, this kind of stuff is maybe the kind of thing where it's best to suppress a mental eye roll and just ignore it. Focus on the good stuff, etc. Unless this is just the tip of the iceberg and you really think he's maybe not such a good guy or not so skilled.