Hi...
Heres some experience from a lad whos used nearly 15 litres of the stuff!.. Its Brilliant paint, You can spray, roller or Brush it on as said. I did my 2a late last year in the cold and frost and although its not perfect heres the finish..
(Dont ask about the little toy 90

It was a photo taken for LRM)
I Carried out a baremetal respray, I'll admit I should have used etch primer and I didnt, But the surface was keyed so much it really wasnt nessesary. I used a litre of paddocks grey primer, And Testrosyl red grade thinners for the base coat then it showed up any areas needing work, Then another 2 coats of primer (Used 50-50 thinners to paint which is the max you should mix too or your paint will just dull within a year!) Then used paddocks masai red paint.. Aprox 40-60 and 3 coats although I wish I had given it a 4th but I'tll probably get done again in a year or twos time..
I brush painted the uppermost part of the roof, But sprayed the sides, at the same time did the catflap and gave the top a quick rub down and a spray over.. Good tip is to buy a tin for spraying and another for brushing only.. I havent yet used a roller but I am going to give it a try soon just to see what finish I can achieve..
Well take your time with it and you'll come out with a finish to be proud of, Also get some paint prep wipes and rubbing pads from halfords.. they are a god send! And DONT use different thinners or paint brands at all!. My bonnet and front apron and wingtops which were sprayed with a different make of primer came out wrong and rough.. Although I have swapped the bonnet and I covered up the wings with Gay plate tops..
Also Paddocks paint is Brilliant for brushing..
Now bear in mind my truck used to look like this..
All in all, Its the best paint I have ever used!