Wherevver you see a smiley you like just right click on it and select "save image as" and save it somewhere you can easily find it and then upload it via ftp to your sites image folder and then go into the AdminCP and on the Home tab on the left side go to Smilies and then click on that then on the next page click on Add Smilie and you will put the address for the smilie in there that corresponds to where it is located on your server and then add the ativation word or sybols and then you are done. Hope this helps.
What limits? Check out the smiley box on http://tgn.tv/community/ The smiley box on those forums (the one that I am the Head Admin on) auto re-sizes to accommodate the number and size of smileys I put into it. Also when you go to add smilies in the AdminCP you can actually re-size them to be the same size as all the other smilies.