Hi rs
1st question about safe working at hight...You should look back through some of the threads on this forum. Every day, almost, the issue is raised. Look back gen yourself up a bit that way. Lots of helpful website links on some of the posts too, directing you to the regulations.
2nd question=same as first really. There is no easy way to clean 3rd storey, apart from getting a pole system, easier.
3rd question I wouldn't bother trying to get standing orders for small amounts ie. £10-£20 I don't think domestic customers would commit. But commercial will, so go for that.
Hope that helps. Hope you're not starting round the corner from me, cos I'm being a bit lazy today!
Pj