I have created a Grouped product (think Tshirt with size and color) and associated the right products with drop downs for size and color.
Do you mean Configurable rather than Grouped product? (Grouped products are the ones where as a user you type in how many of each subproduct you want, eg http://demo.magentocommerce.com/magento-red-furniture-set.html )
1) The price range from the simple products associated with this configurable product
You’ve already seen it, but for the benefit of others (and to plug my own work ) try using this extension which does just that.
2) Use “In stock” as default but then change once a drop down is selected for size and color that may be out of stock
In that extension it hides options that would result in out of stock simple products being offered to the user. It probably wouldn’t be that difficult to modify it to show options from out of stock items too, and then show a user an error if they tried to buy it (this error is actually already caught if a product becomes out of stock in-between a user loading the product page and adding a product to their cart, so you’d just need to change the rules for which products are used to generate the product options), but the user experience wouldn’t necessarily be very nice this way I don’t think?
3) on the configurable product show all the individual product images