Multiple Problems; potential damp, external floor and walls

I bought a house 2 years ago, aged around 1920 I think. On the surveyor report they mentioned a crack in the external wall which is fine (no movement). The crack is mirrored internally too and I'd like a quote to fix this but: - I get wet patches on another wall at the back of the house which suggests potential damp I think but it looks like a damp course has been done already - the floor outside needs relaying and I'm not sure if this is also a source of damp I don't know what to do first and what tradesmen to ask to make sure I get everything fixed in the correct order. Any help appreciated.