Finished the game with all the ending,it has basically all the NTRmen types:BBC,shota,ex-bf (who doesn't like the nts thing),hobo,ugly bastard,colleague.
In this game you basically walk the thin line between nts and ntr and you need to balance thing or things would get bad,there is a bad ending related to each character (the ex bf one is the worst imo) and a good ending.
The length depends on how much fast you read text and gloss over things but it's around 1-->1:30 hour-ish.
My advice is to just play the game normally towards the good ending (don't try to go for a specific bad ending),it's designed in a way that you can see all the endings (the good one and bad ones) around the same save
If the game is too hard,you can save scum for more money (so you can restore a larger chunk of love meter )