1. According to the PHB, a lance deals double damage if used while mounted - every time, even if not charging. When charging
on a mount the wielder doubles (i.e. triples) that damage. So, in regards to your question: true, you can't set a lance against a charging opponent, but OTOH, if you're mounted, you can
always strike the opponent for double damage.
2. Maybe it has something to do with the way you have to hold it... You have to be flying after all, but you're reading it right, IMO. According to RAW, it's not a reach weapon.
3. In 3.0E-3.5E the dagger became the throwing dagger when they added a range increment. IIRC throwing daggers were ruled in AD&D.
There are many discussions online about mixing up the stats for darts and daggers, and applying them to throwing knives, but that's homebrew.
EDIT: maybe
this is what you saw...
BTW, daggers are simple weapons.