When I insert a new item (dock, shelf, start menu) and I pick the item type (program, folder, file, or any location on my PC), then I have to type in the path to it in the field on the properties window. It would be helpful to have a browse button to browse to the file/folder path.

There is - when you have the 'New Item Properties' window open, there's a 'Find Item' button near the bottom of the window.

Easier still, in most cases - just use drag-and-drop.