Hello,
1. Please provide URL of page with the sider and temporary wp-admin access, so we can take a closer look.
2. Sometimes when you import demo with a great number of the images the server timeout is not enough to import all the media that demo has and this error occurred. You can choose the demo import again and at the demo content installation step don’t check all but media only https://gyazo.com/647b0452f7c5d8ddb3ebcf966506dcc0
3. There is no such possibility, right now. You can submit a request here – https://www.8theme.com/taskboard/
Regards