There are several 'evil' female vampires you can fall to, and you'll get the taste of it next month
. Virgil is the main antagonist, but you won't meet him personally until very late in the game. If you're interested in corruption ending, then yes, there will be options that aren't related to him.
We'll add a tutorial about the stats in the next update. Confidence is how assertive Alex is. It indeed affects choices and scene variation - if you have low confidence, you may fail to resist a vampire trying to charm you. Insight/Combat/Athletics are tested when you take some actions. On top of that, Insight reveals what other characters might think and gives you additional information when you make decisions.