Owners normally appoint the auditor at the AGM, so most switches take effect for the next year-end. If your current auditor resigns or the position is vacant, different rules apply.
Yes. A professional handover between auditors is standard practice and expected under professional rules.
Your proposal states the fee upfront, including any first-year work on opening balances.
Not before you have a proposal. Once the board decides, we will guide you on the notice and consent letter.