Heavy post processing effect on print
 

Looking for some guidance,

I'm going to be manipulating images (CS2) from basic color adjustment layers and b&w conversions but also want to pursue compositing images into a final print.
Print size targets are 8X10 minumum up to 11X14.

Images will be digitally captures as hi-res jpegs. RAW not an option.

Are my final print sizes realistic without displaying artifacts, etc?
What, in addition to a properly captured initial image, can I do in PS to maintain a high final print quality ?

Thanks for your help.
Bob