Welcome to the WCHA.
Your canoe is in remarkably good shape, and should be readily restored to a beautiful condition.
That said, it is very unlikely that the canvas and paint are original, especially since this canoe served time as a livery canoe. Repainting and recanvasing are considered ordinary maintenance on a canoe (like getting new tires on a car). Your paint is quite severely cracked, at least in part because the paint has likely been recoated several times while doing rental duty. I would strongly recommend that you remove and replace the old canvas, and then repaint – with any color or design you wish.
While it is possible to repaint a canoe with paint cracked and crackled like yours, it would be only a stop-gap measure that would get you only a few years. And it will simply not look as good as a new canvas/paint job. And if paint is actually flaking off, repainting will not work. Here are links to some discussions in these forums about painting over old cracked or chipped paint when you want the paint to last only a season or three or five before re-canvasing:
http://forums.wcha.org/showthread.php?t=5790 see pp. 2-3 of this thread
http://forums.wcha.org/showthread.php?7769-Painting-over-existing-paint&p=41339#post41339
http://forums.wcha.org/showthread.php?5933-quot-Minor-quot-Restoration-advice-please&p=32358#post32358
http://forums.wcha.org/showthread.php?7775-Temp-repair-to-bare-spot-on-canvas&p=41357#post41357
http://forums.wcha.org/showthread.php?7619-time-is-not-on-my-side!&p=40689#post40689
http://forums.wcha.org/showthread.php?8564-Smoothing-Canvas/page2 starting at post 12, on bondo spot putty
http://forums.wcha.org/showthread.php?6607-sanding-or-not&p=35286#post35286
http://forums.wcha.org/showthread.php?8906-Repaint-Tips
Recanvasing is not as difficult as it might seem, and someone with your background and skills should have no trouble with the task.
New paint and canvas are really called for, and unless you are desperate to use the canoe this coming year, I would recommend against the stop-gap approach.
The varnish on the interior of your canoe is quite well worn, and at a minimum, a new coat of good marine varnish with high ultra-violet additives is called for. Varnish is not just decorative – it protects against wear and ultra-violet damage to the soft cedar of the canoe. Better would be to strip the existing finish and put the new varnish over clean, sound wood. The advantages of stripping old varnish with the canvas off is: 1) you do not have to worry about trapping chemicals or new varnish behind the old canvas; 2) you can remove any and all sand, dirt, and other crud that has likely accumulated between the canvas and the hull planking; and 3) you can closely examine the wood of the hull (both ribs and planking) for damage that is sometimes not readily visible even after a good wash-down. The ideal time to do this is when an old canvas is removed, but before a new canvas is put on.
If you do proceed to simply wash the canoe out, I would not use a steam cleaner. A gentle water rinse using a garden hose without any nozzle, or a light scrubbing with a sponge (perhaps using TSP) would be the most that I would do. Any sort of pressure washing risks damaging the soft cedar of the cane and may drift dirt into and/or behind the planking or between the ribs and planking. Further, much of the wood in a canoe has been purposely bent to a greater or lesser degree – and I would worry that the heat of steam might adversely affect the shape of the canoe (not likely a problem, but why risk it?).
Before you make any decision about how to proceed (either doing the work yourself or hiring a professional for some or all of the work), you should get, or at least look at, one of these three good sources of information about canoe restoration:
The Wood and Canvas Canoe: A Complete Guide to its History, Construction, Restoration, and Maintenance by Rollin Thurlow and Jerry Stelmok
Building the Maine Guide Canoe by Jerry Stelmok
This Old Canoe: How To Restore Your Wood-Canvas Canoe, by Mike Elliott
The first is often called the "bible" of canoe repair, restoration, and maintenance; the second is an excellent study of the wooden/canvas canoe and its construction. The third is the most recently published and has been well received.
These books are available from the WCHA store, are often on eBay, or from Amazon.
Of course, you can always ask questions here on the forums. There is a good deal of information here, and we are happy to share and pass on what we have learned.
The WCHA has a very active and knowledgeable membership in Michigan. You might consider getting in touch with Craig Kitchen, our chapter coordinator, for information about chapter activities.
Good luck with your very nice canoe.
Greg