Articles are already downloaded and stored in a SQLite database. The only items not cached to disk are the images, but that option may be added later. You can download enclosures either manually using a long-press on the link, or automatically by enabling the 'Download enclosures automatically' option when adding a feed. Regarding sync from desktop, you can source articles from wherever you like using the custom command option when adding a feed, so it's possible to use a script that retrieves the articles stored on your desktop machine.