no mean to go off topic mate but if your having trouble using other things try Paint.net from http://www.filehippo.com/download_p...4e19ecbf44a86f/ its not got any viruses in it i find it simple to use and works good
Hmm.. I'm really not sure about the size issue. Do you mean the file size or the actual image size? If it's file size, then it may be related to the format you're saving in as well as the quality settings you choose. GIMP has pretty extensive options even if you're just saving something as a JPG.
Your layer options are located in the Layers Dialogue (Make sure you've got the first tab selected in the newer versions of GIMP and not the Channels tab, paths tab, etc.). Once you've got that up, you can change the Mode type of the current layer. That's where you'll find the hard/soft light, overlay, etc.
