Progress

Here's the progress so far:

-Customers sync/detect changes and update (done)
-Tax rates sync (done)
-Sync orders (done)
-Sku, name, prices, cost, tax assigned for simple products(done)
-Sync stock to checkoutapp (done...by auto create a purchase order like checkoutapp's own products import from file feature)
-Sync variations to checkoutapp (product attributes in magento) (done)
-Sync stock back to Magento (done)
-Automate these actions somehow, like with cron jobs or trigger after event (done...only implemented for auto order push and auto import stock to update magento's)
-Create a kind of log of each process/sync done for revising and error handling/fixing situations (done...only for the automated features, logs errors and success)

I'm planning to release a beta version asap, and a demo video.