Most Helpful Guy
probably best to ask the guy. See, guys don't think much about this stuff... we'll just start noticing things left behind and think you forgot it and maybe even ask about it. lols, some guys believe women who do this are claiming their territory, because if they see another hair brush the date could stop at that moment.
Most Helpful Girl
As far as staying over, totally up to you. If it's been less than a month, some guys will get freaked out and think you're moving too fast if you're leaving stuff at their place.