No, you have to download 0.11v, then 0.11v->0.12v update, then bugfix3. Sorry for the confusion, but this way you don't have to download everything if you played the previous versions.
You can't complete it that way, because there aren't any quests for Corruption Of Kiley Duncan 3 and 4 (it is not completed yet). But you can complete them by using cheat system.
You have to download the bugfix, otherwise you can't see the pole in the Pawn shop's wares. And the complete button was bugged, thanks for mentioning it! I'm uploading bugfix4 now.
You are always playing as one character (MC - main character). But you can choose which story you will follow. For example: If you don't like Kiley (older step-sister), you can ignore her completely. If you only like Michelle, you can play just her story etc.
Strength is useless right now, that's why it is not displayed. Younger step-sister is not implemented yet, because people were against Dakota Skye being the face behind her character. So I made a poll and you can see it's result on the top of this thread. There will be probably some scenes with her in the next update (but she will be completely avoidable).