You could, but only inter-wiki images can be customised with size and crop parameters in the URL.
Generally, I only use this for small images. The big image used may not work well with all devices, such as on mobile where the image takes up a lot of screen space. On desktop, the image does not show fully, which can be annoying when the image has a lot of details like this one, that are concealed unless I zoom out.
(You may have to use some HTML coding to customised placement, cropping or captions.)
Vignette and Static are two different photo boating websites that Fandom uses. Vignette is the better option if you want photos from other wikis to be included outside of the wiki that the photo is on.
Why would you need users to upload the images here instead of on the wiki itself. Community Central is not meant to be a central database for images. If the images are being uploaded for use on your wiki, they should be uploaded on your wiki; not some other wiki.