Wolf attack speed should be the same as it was in 7.7.4
Both attack speed and back-swing animation delay matter. I think the back-speed is something like 300ms.
Also if the sheep isn't within 185 units from the shepherd when the attack lands it will miss.
That seems like a random number. It's either 192 or 224 in WC3 (check range motion buffer, which I think is added to the range to determine how far the unit can be when the attack lands).
How fast should the illusion move? It currently moves at 500 units per second. I wasn't sure of the mechanics for the illusion so as long as the terrain is blocked it will continue to move forward until it finds a spot or 10 seconds. Should it not go uphill?
You can check the speed in WC3. It'd be listed under the ability. The mechanics for imaging is relatively complicated. First, it scans the area from origin for a viable area to place the unit, up to a max of like 7.5 farms (scanning in a spiral grid). Then it checks if the area is the same level as the source. If it isn't, it then scans from there up to a max of 5.5 farms for a viable area of the same level. Illusions can only land up hills if a space becomes occupied while the image is trying to be placed. The Bulldog map that makes testing image physics relatively simple (the one with the long hill jump).
I don't exactly remember all of these numbers and don't have WC3 installed anymore. But they should all be verifiable.