I am a novice modeller but with a big wishes to learn modelling skills

I bought a Dragon model 6231 British Sherman Mk. III Sicily and began to assemble it. As a reference guide i decided to use ArmorPhotogallery 11 but
it is something that i cannot understand in the model. The picture must show the trouble. I glued together suspension parts and try to fit it with hull. There are very big gap and step between hull and transmission cover. How it could be on the real tank?
Also can i assemble this type of Sherman tank mainly from the box or i need any correction parts here?
And another question is about glueing and painting wheels and suspension. Please give me the advice about order in which i must paint and assemble it.
Thank you very much!
Sincerely,
Aleksey.
