Stupid PS Question

[Sadist]

Like tilt mentioned up-thread, it would really help if you could upload some of your work so we can see what's going on...
there is a lot of knowledge to draw on here, but trying to visualize the problems you are describing can be a bit difficult. This is mostly because there is never really any one single correct way to fix a given problem, it really comes down to preferred techniques in the end. And please don't be shy about uploading the WIPs...that's what this part of the is for

[tilt]

concerning resolution it really depends on what you want to do with your map. But remember, you can always scale down - but not scale up, so you're setting your maximum when you choose resolution. For everytime you go up one step on the "ladder" below you quadruple your filesize and the file gets heavier to handle
For screen 72 dpi
For "home" print 150 dpi
For professional printing 300 dpi

and you can go higher than that even
so at 300 dpi and inch is 300 pixels x 300 pixels, so you can with a quick calculation see that your screen quickly wont be big enough to see the whole image at 100 percent even if you just have a little tiny itsy bitsy map.