How many parts vinegar to water for using in cleaning...

I use a 1:1 ratio. I also like to add a little lavender, tea tree or lemon oil: Sage & Simple: homemade lavender cleaner

I can't find scouring powder in Denmark, so I use baking soda like Ajax, Comet, etc. to scrub sinks.

Here's a recipe you can use to clear a clogged drain, it uses baking soda, vinegar and borax: Sage & Simple: diy drain cleaner

Works much better than the commercial drain cleaners, and is quite cheap too!