The problem with gallery 3.0.10 not installing in dnn 3.1 is due to a wrong .dnn file in the zipfile (businesscontrollerclass)
Until there is new a release you can replace the line with the businesscontrollerclass with this one :
<businesscontrollerclass>DotNetNuke.Modules.Gallery.Controller, DotNetNuke.Modules.Gallery</businesscontrollerclass>
Make sure you change the .dnn file WITHIN the zip file, not the one in the gallery directory as that one gets overwritten with the file from the zipfile of course)!