The AvaTax setup in BV Commerce 2013 is pretty simple. The only configuration that you need to do beyond entering your account credentials (Options >> Site Settings >> Avalara Tax Setup) is to setup your taxes (Options >> Site Settings >> Taxes). The actual tax rate that you enter for each location is irrelevant; the reason we require this is to save API calls to Avalara for locations where taxes are not applicable. For example, our office is located in Pennsylvania. I would need to setup a tax rule in BVC for Pennsylvania. Again, the tax rate that you enter isn't used because Avalara is calculating it.

All other configuration is done on the Avalara side of things. If you do use tax classes in BVC the tax class name is passed to Avalara for each line item in the order. For this to work properly you would need to have configured the tax codes on the Avalara side.

This is a problem that we discovered recently. The BVC integration has always been this way so I'm not sure if Avalara changed something or if this was always incorrect. Either way, this will be corrected in the next release.

No, sorry. We do not have an import/export or pre-written script to import tax classes. The database schema is pretty simple, though, so it would not be very difficult to script this.