Roddyrail

I am just starting to weather a locomotive, something I've never done before. I have Humbrol Weathering Powders pack but have not idea what I use to fix the powder in place. Is there a suitable varnish that I should purchase?

I'm new and constructing a matrac layout. Question, what are droppers?

Thank you for your help.

I've just purchased Hornby's Santa Express for my grandson and I'm find that it's extremely difficult to connect the new track sections together. Are there any tips here like using WD40!

Thank you very much MO, that was useful and I'll follow your suggestion Roddyrail

Please bare with me on a simple question as I'm new to modelling. Question - does a track layout have to be a circle of oval to work electrically. I have a single straight length of track that I would like to electrify. Can I do that?