Why do you say Gai is from another year of gennin? There's no proof of this. We've never seen his 3 man team, so they could have come from any generation. Most likely he was the same year as Kakashi seeing as they are rivals and they seem to have grown up together.

If anything, it's Kurenai who is from a different year, younger than the rest, because they describe her as a rookie jounin. But again, there's no proof.

I'd say Kakashi is more of an all-rounder rather than a Ninjutsu specialist. His Sharingan gives him better-than-average Genjutsu capabilities, and we've seen him use Taijutsu fairly effectively at times.