Double extension is not allowed. Make sure there is only one "dot" in filename, and its file extension. File "some.photos.2018.rar" won't work. On the other hand, if you name it "some_photos-2018.rar" it will work just fine. This is for security purposes.
Forever. Unless they do not meet our Terms of Service or:
You can upload any file up to 500mb of size. Exe and bat files are not allowed. Zip them if you must!