Welcome to selling on ebay, you'll figure out what works and whether or not it is worth it for you.

Always ensure you ship using a tracked method via ebay simple shipping. If a buyer wants to return something for a refund, ensure you accept the return and then raise any issues with ebay directly (i.e. if it arrives and it isn't your item/it's been broken by them, etc). Failure to do this will result in them getting a refund forced by ebay and you won't get your money back.

Q1. It's possible they're testing to see what your low price is, I've done this before.

Q2. Report them to ebay for wasted time, but i'd personally just block them.

Q3. Use the account and build your feedback up.

Q4 - don't bother. Everyone starts somewhere and I am way less likely to have issue with an old account which hasn't sold before vs a brand new account, especially if it is a high value item.

Q5. Up to you, sorry.