If you extract this big image file to a real partition (like ext3 formatted sd card), you should notice speedup. The reboots are related to buggy kernel input/output operation handling I guess. Try reading the whole thread http://talk.maemo.org/showthread.php?t=69973&page=1 (it's 17 pages, but people suggest there some different settings, than in the first post, you may want to try them). Generally, you can just grab the code from first post of that thread and pase it into terminal as superuser ("root"), you should get rid of reboots (if not, try code from later posts). If you want to understand these commands you may also want to read whole thread and maybe ask some questions there.

No problem, Dude, if you have any more questions, you can PM me. I'm not a guru, but I consider myself power Linux user. Enjoy your N900.