This could be long winded, so bear with me!
The shape of the bow is important. the standard fault of almost all modern boats is a slab sided bow. If you look at working boats out of the water you can see that the lower part of the bow sweeps around in a curve which minimise the drag of the boat when moving- modern boats dont have this (there are some that do, but they are very rare and I've only ever seen one)
Most (genuine) working boats have very little wash when moving, so they are the best place to look for no-wash bows. To see poor examples of bow shape look at springers and the supposed "aerodynamic" boats that roar along. Their bows are designed to cut through the water rather than move with it, which causes massive wash and bow waves due to dissplacment.
The speed is an important factor to consider if you are on a boat with a poor shape - the faster the boat, the higher proportion of block-water-shift (water moving in a block due to it not having enough time/space for the particles to move)
With most old working boats you don't have to factor this worry in.
I'm not sure what you mean by the shape of the swim - a boats swim is her ability to move through the water, "how she swims"
If you mean the shape of the stern, that really doesnt affect the wash much. It can affect the drag, forcing the engine to work at a higher rev count, moving the prop more, causing the props wash to increase, which joins the wash caused by the boats passage and giving it more momentum- but this will only happen if the boats wash has a certain momentum.
The size of the prop affects the speed and power of the boat but, as outlined above, the props wash doesnt do much on its own.
The length of the boat doesnt effect the wash greatly. A longer boat is going to have a larger displacement ratio, but it is also going to block the shift of water longer - allowing the wash to loose momentum. vice versa for a short boat.
The depth of the water is significant when considered with what depth the the boat draws (how deep she sits in the water) for example: a boat drawing 2"9 in 3" of water is going to have an increased drag-power ratio which affects the wash by increasing it; but the depth of the water is going to affect the swim, slowing the boat down considerably - effectivly lowering the wash.
The best way to minimise wash is to travel at about 3 knots and to stay in the middle of the canal.
Does that help you?