However, I have no idea how to select a placement. Why would I choose ceiling mount vs wall mount? Like is there an "ideal" place to mount the fan? If wall mounted - high or low on the wall? Near a corner or in the middle of the wall? If ceiling mounted, near the center of the room? Corners? Wall centers?
The fans you've referenced are fundamentally the same. I.e. the "ceiling" version still is designed to move air horizontally (as opposed to what we usually think of as a "ceiling" fan).
I would say that the choice of ceiling vs. wall mount is primarily going to be driven by the exact location you think the fan will be most useful, and the convenience of installation (e.g. where you already have existing wiring). It will have more to do with what's the best location to mount the fan, rather than any particular aspect of operation.
Also, I assume oscillating is "better" than fixed (again, the price is only marginally more)? Is just "better airflow"? Are there any downsides?
Oscillation is a question of how you want to use the fan. An oscillating fan does a couple of things that a stationary fan does not:
- It provides air movement over a broader area of the room, especially useful if the intent is to provide a breeze for two or more people at the same time, but who will be working in different areas. (Of course, you could accomplish the same with more than one fan, but that increases cost.)
- It will help mix the air in the room more evenly. Depending on the nature of the heat, this may or may not be of concern. (Note that even a stationary fan can accomplish this to some extent, and other brands of fans, like Vornado, which specifically drive the air in a more vortex-like "beam" can do this even more effectively, as the motion of the air is better-preserved even after hitting a wall or ceiling.)
Bottom line on those two points: there's a reason the fans are offered in different configurations, and the reason is mainly because different users have different needs. You'll have to think about how the space is to be used, how you expect to use the fan, and what would be involved in installing the fan, and use that information to drive your decision. Within the four-option matrix (i.e. the four combinations of oscillating or not and wall or ceiling mount), there is no best option overall. It just depends.
As far as locating the fan, again that will depend on your specific need. If you want a stationary fan to blow on a particular spot, then a location at the right distance from that spot where the fan can be properly positioned would be best. If you just want to mix the air in the room, an oscillating fan positioned near a wall, or maybe up to 1/3rd of the width of the room (depending on how large the space actually is), might be better.
At the end of the day, you might find that practical considerations related to where you have power and structure available for mounting are the primary factor.
I note that in one comment, you mention that there is living space above. That could also be a consideration. It might be easier to control noise infiltrating the living space if you mount the fan on the wall rather than the ceiling. Assuming that's a concern, of course.
Last gotcha - I have a door to an air conditioned house. Would keeping that door open while working (in a further attempt to cool the garage) be useful? If so, would it change the placement choice?
Unless you plan to hang the fan directly in the doorway, and preferably on the cold side of the doorway, it's unlikely that the fan would help much with mixing the air conditioned air with the warm garage air.
On a broader note: it's important keep in mind what a fan can and cannot do. The fan is not going to change the temperature of the room. In fact, running the electric motor is going to increase the average temperature a hair.
What the fan can do is even out the hot spots in the room, if any (e.g. you are using welding equipment, or doing something else that generates heat, or maybe there's a spot in the room that gets a lot more sunlight), and can provide a breeze to aid in cooling a person's body, taking advantage of the body's own mechanisms for dealing with heat (i.e. sweating and dilating blood vessels).
Even with a fan, if you're working and the room is hot, you're going to feel hot. Staying hydrated will be at least as important as any other consideration. If you really want to cool the room, you need something else that will actually change the temperature, rather than just your perception of it.
For somewhere between the same price as the fan you're looking at and less than double that price, you could get a window-mount or portable A/C unit. At the higher end of that range, you could even get a dual-mode (i.e. heat pump) model that will heat the space in the winter if needed.
At the lower of the scale, you also have the option of exhaust fans. Depending on the climate in your area and why the garage gets hot in the first place and whether you can provide an effective source of make-up air for one, an exhaust fan could be used to keep the space cool enough that a fan to actually move air in the space isn't needed, or at least would be a lot more effective.
Don't get me wrong: fans that just move air around have their use. I find them especially useful for spaces where conditioning isn't even possible (e.g. the space isn't even fully enclosed), as well as an accessory to be used in combination with conditioning methods (because it's always still helpful to mix the air in the room, conditioned or not). But if your primary complaint is just that the space is hot, a fan might not be the most cost-effective solution from a price/performance perspective, even taking into account the significantly reduced operating costs as compared to A/C.