Not mutually exclusive.
No.
And of course it is (a good microscope actually allows you to see that 'clearly' in the leaves).
Did you actually come to those conclusions 'after' you read the doc (uhm for example the The Translocation of Phloem section)?
Without leaves there is no photosynthate (the product of photosynthesis, energy stored in the form of sugar) for the phloem to translocate. Leaves aren't just essential to translocation (through both xylem and phloem, bi-directial with leaves often either being the destination or origin), they are essential to ALL the processes in a plant which are all chemical processes requiring energy. Most people have heard the comparison of leaves to solar panels but it seems many don't realize how true that comparison is (and there's no backup line to a grid...).