Hi Daniel
Every success with your build, and you will have fun learning stuff along the way.
Some drawing sets are better than others, but always treat them as an arrangement of dimensions (that you need to double check). With all builds you need to come to your own views on the sequence of steps, how things are best fitted, materials, appropriate fixings, etc, etc.
There is a lot more understanding we all need that will never be in the drawings, nor in any write-up that the designer might have published, although such descriptions are very helpful. For example, quartering wheels and getting the valves to work. You might find this by reading as much as you can, perhaps working back through Model Engineer articles (libraries at the local ME club), looking through web site builds and write-ups by others, and talking to experienced engineers when you can. There are also model build video guides being published on YouTube.
This forum is great for its range of engineering discussion but, as Dave says above, try joining the (smaller) MECH forum if you want to ask a specific 5" build question.
Norm