Hi Dylan,
Yes, using CSS you can change the field names (I’ll see if I can dig out this post)
They’re also currently working on a multiple trading style at the moment. I’m not sure how this will work, but it is limited to just 5 styles.
I’m wondering if Affinity would be a better option, but this would mean each account would have full control over their own account. Perhaps @Glenn could advise on the best option?
In terms of the development - I’ll send you a PM now.
Edit
For the label customisation, see this topic, although this would only apply to invoices
http://community.quickfile.co.uk/t/customise-any-invoice-or-estimate-label-using-css/3882