The crime library linked above will give a lot of confirmed information about particular killers and their crimes, victims, methodology and trials.
This website has a few well-known facts about serial killers: http://website.lineone.net/~tymaloney/info.htm
It looks like he’s referenced a few books you might be able to find at the library. I didn’t scour the site though and cannot vouch for the validity of all of the information.
This is important to know:
* A serial killer is someone who commits three or more murders over an extended period of time with cooling-off periods in between. In between their crimes, they appear to be quite normal, a state which Hervey Cleckley and Robert Hare call the "mask of sanity." There is often — but not always — a sexual element to the murders.
* A mass murderer, on the other hand, is an individual who commits multiple murders in a single event and in one location. The perpetrators sometimes commit suicide, therefore knowledge of their state of mind and what triggers their actions is often left to speculation. Mass murderers who are caught sometimes claim they cannot clearly remember the event.
* A spree killer commits multiple murders in different locations over a period of time that may vary from a few hours to several days. Unlike serial killers, however, they do not revert to their normal behavior in between slayings.
One place you can find that information is at Answers - The Most Trusted Place for Answering Life's Questions though it is also in criminology and psychology textbooks.
Your first premise may not be entirely plausible. It’s kind of a stretch. It’s unlikely that if a person does x, he would be unlikely to do y when x and y equal types of restraint or violence. What you may need to consider is that your serial killer will likely have a very particular pattern.
For example, Ted Bundy targeted generally college aged women. He was very good at gaining their trust because he was charming and good looking. He usually used very simplistic methods of picking the girls up - lost puppies (no kidding) and the girls’ sympathy. He frequently wore a fake cast and pretended he needed help until he got the girls into his car.
It’s widely accepted that serial killers are generally white males (at least if they are killing white people), between the ages of 19-40…I could have that a little off but that is not too far off, could be 18-35. That’s all just based on who they have caught though…the Son of Sam, Ed Gein, Ted Bundy, Jeffrey Dahmer. There have been a few women, most notably Aileen Wuornos. There’s tons of info out there, but double and triple check the sources, it’s not all accurate.