Hey there. No exact estimate on playtime, but I'd like to have at least 16 levels with 4 difficulties to choose from. Hell, if things go well, the plan is to have a total of four episodes, each one containing eight levels.
Don't worry, there will definitely be futa on futa content. Remember that gigantic demon lady you saw in the main menu? She'll appear as an enemy in later levels. I might add more futa enemies if there's a demand for it. Even futa on male content is up for debate.