Length: depends on reading speed, whether you just play 1 route so far or want to see all of the content, and if you want to grind the random adventure, probably about 1.5-2h if you read at a decent speed and only do 1 route, 2-2.5 if you want to see all content and fast-forward the stuff you already read, 3+ if you decide to grind; I don't recommend it, but that is your decision to make.
Romance: there are... I think 8 sex scenes at the moment (some mutually exclusive within a playthrough), and a decent bit of romance; the game focuses a lot on the relationships, but there's also a lot of casual and romantic sex once you get past the initial bits. There hasn't been enough time to do a start-to-finish romance of course, but some development and 0.5 will add a fair chunk more, and long term that is one of my primary goals.
Character creation: at the start of the game you pick between magic, melee, or magic swordsman, and between 4 weapons and 4 elements depending on the first choice. You have 8 stats you can customize, various traits depending on your stats, etc. 0.5 or 0.6 will bring in learning additional weapons/elements from allies and more abilities in general. As that goes live it'll be possible to replicate a paladin vibe (tanky sword and shield guy with light magic), a rainbow element mage, a fast and stealthy assassin, an archetypal fire mage, etc. There are also a lot more weapons (and elements) planned for the future, so longer term you'll be able to go for a Monk or martial artist vibe, rock a warhammer or bow, etc.
I dunno if this is the best comparison, but think something like D&D or Corruption of Champions, where the mechanical RPG aspects are a major focus and there's a wide variety of builds.