Nothing like the feeling of making something for yourself.
I know I am getting excited with my build,so I know how you feel.There will be times when you wonder what were you thinking.Just walk away ,take a deep breath ,and work on another part of it.
on your pics size this is what I do.
Your computer has "paint" program.
1st open it up.
2nd select the file tab,go down to open.click it.then find the folder or wherever you have your picture.select the pic you want then click open on the window with the pic you want.
3rd your pic will be huge,So go to the tab at the top of the paint that says "image" click it ,and then select "resize/skew"
4th enter 15 in the horizontal ,and vertical boxs then hit enter.
wallaaaa your pic is now shrunk.Go back to the file button,and then select" save as" and then rename it.
5th
Now go and upload that pic to your post ,and it will work fine.Thats how I have done all mine on my build thread.
Way easier than downloading some program to do it.