Diary and glasses

No. Retainers are monthly and you can stop at the end of any month. There is no setup fee and no notice period beyond the month you are in.

They roll over once, so a quiet month is not money burnt. They do not accumulate indefinitely, because that would mean I could not plan capacity.

Almost certainly. If it is genuinely unusual I will say so before you commit, and I will learn it on my time rather than yours.

Yes. I do not subcontract and I cap the client list at nine so that I can still remember how everybody likes things done.

Invoicing, chasing and reconciliation, yes. I do not hold banking credentials or make payments, which protects both of us.