Can't help with most of your fruits as I have as much idea as you, but the banana lady at the markets told me that you can store bananas in the fridge once they're ripe for a couple of days wrapped in 2 layers of bubble wrap. The skin still darkens, but they're OK inside. I find after 3 or 4 of days they start going soft even if they are wrapped - but DS will eat them anyway.

Oranges i don't think ripen once they're picked so I put them straight in the fridge.

Pears, plums, nectarines & peaches I leave out until I think they're ripe and then put them in the fridge. There are vairieties of pears & nectarine that you're supposed to eat crunchy though.

Was that any help?