professor oak only appears in diamond but if you want to meet him try sapphire version
same as in leaf green or fire red. in pallet town.
nope but you can on Pokemon platinum
There isn't a flute maker in Pokemon diamond as far as I know.
penis
The house that is downward of the Pokemon center in Canalave city
In Hearthome, next to the Pokemon Center.
You go to the Survival Area and his house is on the left of the Pokemon center
Lucasas's house is the house with the mailbox in sandgem town.
He should be in his house.
the old chatau
heartthrome city house next to the Pokemon center
in Pokemon diamond you can only use it in battle since your cave/house/thing is underground