Hi there Will, just seeing your email summary.
Always easier to get our attention by email but Andrew and I are keen to solve many of the issues you speak of.
Were dependent on the structure of Shopify for point 1, gift cards are a very complex issue and one that we have been thinking of for a long time. This would resolve many of the negative fund amount concerns. Its hard to predict the timing of this specific feature as it must be perfect and highly useful. Stay tuned for this one
For your second question of barcodes: from our standpoint on day 1 it was a bit unimportant to add barcodes, as we get more interest we will be more keen to match this with a feature in Shopify that can match our customers needs. For now you can generate barcodes using the label printing software. The label printer is the Dymo LabelWriter 450 and it comes with its own software to create bespoke barcodes to your specific inventory numbers or barcode scheme. As the app rolls out we might find that more customers require this but we found many free solutions included with the label printers. Would that work for you or is there a different need your store has?
With Shopify Payments we imagined this to be a seamless process, cash would be the only inaccuracy to calculate. Are you taking with an external merchant terminal?
Your option to display the different received amounts is very good I think me and Andrew can certainly discuss this with the POS team this week and assess what the best solution might be.
The reporting options you are also asking about I believe this can be all viewed with DeepMine http://apps.shopify.com/deepmine and also in the unlimited package for Shopify. Custom reports can be generated and the Type, Vendor and Title can all be used. Tags are not included in our reports right now.
Thanks for your ideas and suggestions about the reports and use cases that you've experienced, it really helps
Feel free to email me at massaad@shopify.com if you (or anyone else reading) come across any other questions