Looking for some questions answered around self employment

*UK replies only*

Hi

So I'm currently working part time and looking to set up my own fashion business on the side, but need some questions answered. Looking to be a soletrader rather than a ltd company.

1. Can I work part time and be self employed?
2. What and how do I can back VAT on the stock I buy? If so when do I get this?
3. Can I use another address as my 'registered address' rather than my home address?
4. Do I need a business account, or do you recommend I have one etc?
5. When do I actually need to let HMRC know, immediately or when I have made money or profit etc? (If later can I claim VAT back on stock bought previously?)
6. How do I keep records of my invoices, expenses etc? An example would be handy

Thanks