Thank you for your quick reply.
Okay - my photoshop is set up as Srgb but when I went file open for the template I chose RGB color mode.
If I don't resize each image first, do I just transform it to the correct size. It is very tiny when I place in the A0 template. (my A0 template is 14043px x 9933px at 300ppi) so I was worried about the quality.
Dumb question - how do I resize without cropping? I have crop presets set up for A2, A1 etc at 300 ppi, is that what you mean?
Yes, one file is type and one is the image. Well, when I say type, it is an image of type that I then edit in photoshop, and sometimes fill with black or white depending on what look I want.
Yes images will be for sale, and printed through a lab. I will test at a lab but it won't always necessarily be a lab I have control over though - I am yet to work that out. (ie could be societ6 for example where you supply one file and they print at different sizes)