Hi,
1)Since each library has its own set of objects, properties, ...
collections, it depends on libraries your are using in each project.
Now, you can search the online help for 'Excel Object Model' and you'll
find an interesting map of all objects and collections (based on coloring) in
Excel, as well as some 'hierarchy/dependency' between them.
2) ... too extensive but the Object Browser is a place to start. (key F2 or
menu View > Object Browser.
3) DIm MyCol as Collection
Set MyCol = New Collection
''' Collections have 4 sub/functions: Add, COunt, Item , Remove
and look in the online help for examples
On top of that, you can wrap a Collection in a class to make it strongly
types and better control it, like Worksheets which has an Add and COunt like
in COllection, but implements many more subs/functions.
Search the web for 'vba "Collection Class" ' or ' vb6 "Collection Class" '