1 – Relevant = does the evidence help you to gain confidence about the assertion. For example, tracing an invoice to a receivables account gives evidence about the existence of the amount but no evidence about its recoverability (valuation). Reliability = how good. Asking client staff if all inventory is included is not very reliable.
2 Areas of high audit risk require more evidence. It is just a matter of the auditor begin able to give reasonable assurance about the amounts in the FS.
3 An audit procedure is a way in which you collect audit evidence. For example the procedure of inspection gives evidence about existence.