1. Compiler choice usually has a minimal effect - VM used is usually much more influential.
2. Never tried it myself. Rumoured to provide a speedup, but not sure how much..
3. As far as I know, the optimise -O parameter has never actually done anything..
4. Perhaps the <a href="http://web.archive.org/collections/web/advanced.html
">way back machine</a> could help you? A quick look shows the dev section seems to be avalible...
5. Negative/invalid coords should be perfectly fine, pixels should be clipped to the target properly automagically.