Excellently put Stormer.. Your mum was a math's teacher?.. I'm so bad at maths.. I'm actually glad I got to read this as it explained scale way better to me for me to understand it..
As for the threadstarter.. well done to you for posting this question.. and good luck for sorting out your dio. Basically dio scenes and bases take quite a bit of time to set up but the effects are stunning in shots.
As with Bigtattoo people have used playmobil, sylvanian families and other house related dolls furniture for dio sets.
A place called Marauder Inc do things for dio scenes as well bunk beds to bulletin boards etc
Maruader Inc
Check them out for accessories
Rich