Invoicing that keeps up with the job.

Yes. That is the normal shape of trade work, so it is the normal shape here. Invoice the whole accepted quote, a stage with its own lines, or whatever remains at the end; the job tracks what has been invoiced and paid, so the balance is always the real one.

No. The invoice is raised off the job carrying the accepted quote's lines and figures. Totals are always recomputed from the lines, and numbering comes off a sequential series: no gaps, no duplicates, nothing for a tax inspection to wonder about.

Yes. Overdue invoices are chased automatically, and part payments are recorded against the invoice so a deposit already taken is never chased as if it were owed. An invoice is paid or part paid according to the payments recorded on it, never a flag somebody remembered to set.

VAT the way UK trade billing actually works: standard, reduced and 0% rated lines, VAT-inclusive display where you quote gross, and domestic reverse charge when you are Xero-connected, so the rate on the line is the rate in the books. Not VAT registered? The forms put VAT away entirely rather than printing zeros at you.

On Pro, yes. Sent invoices push to Xero automatically, dated the day you raised them, and when your client pays and the payment is reconciled in Xero, Pascal marks the invoice paid. Pascal owns the invoice; Xero owns the money.

Yes. Every emailed invoice carries a link to its own page, so "can you resend it?" stops being a phone call. You can also see whether it has been opened, which changes the tone of the chasing conversation.