question about plot resets/time travelling

so the last time i saved my game was yesterday night, around 9pm in game time on acnl
i'm always cautious when starting a new day in acnl and so i made a new player just to scout the town to see if there was anyone moving in. low and behold someone did, but i closed the game before i saved the new character and started another new character again to see if theyd move somewhere nicer. this time there was no house at all. i currently have 8 villagers.

what i'm asking is, is it possible for there to not be a confirmed villager moving in. just on random times a villager will move in, i have 8 villagers right now and i know when it gets to 9 (correct me if i'm wrong) the only way to get your 10th is through streetpass, going to someone elses town and talking to the villager in boxes etc.

and the most important question. the last time i saved was last night, can i theoretically when loading my mayor say the date is last night + that same time, and it will be exactly that without any problems. that's just so i could get a villager i want (visit someone elses town before 5:58am and then i can reset for that villager instead of just multiple randoms that the game is giving me right now?)

sorry if this didn't make much sense :S any help/answers would be appreciated!

The 9th villager will move in on a random day, so you can go in on a new save file and have a plot, then if you didn't save, the next time you go in with a new safe file, there may or may not be a plot.

You are correct on how the 10th villager moves in.

I don't have experience with your last question, sorry.

The safest way of making sure your 9th slot is free so you can adopt is making a new character and then if there's no plot saving/making the character a a tent. That way you'll know for sure the 9th slot is open and you can adopt with your mayor/delete the character and plot reset your adopted villager tomorrow.