A:Yes, you can customize which feeds to sync here: `feed list` -> `Subscription`. And you can also customize whether to download the images, whether to download the full text, whether to display image title.
A:`Sync` will synchronize all you feeds, and including download images and web pages. But `Refresh` just trigger by pull down the article list. So it just synchronize the current category/feed. Of course if the current list is all items, it will synchronize all your feeds. And `Refresh` won't download images and web pages.
A:`keep unread` just keep unread locally, will not be synchronized to the server. If you clear cache, logout or reinstall the application, you will not be able to retrieve records which keep unread. So temporary use keep unread only.
A:By default, all automatic network operations will be carried out under wifi network. You can find the related settings in `Settings` -> `Sync` -> `Traffic`.