I can chime in on a couple of these:
* Computer Forensics Investigator:
Experience counts for more then anything. Ex-Fed and Ex-Cops are in high demand. My company has ex FBI, Customs / ICE, Local Cops. Their prior employment is almost an instant marketing tactic. We also have some non-fed employees, myself included.
CFCE is the the most sought-after certification, but is only available to law enforcement. CCE and EnCE are also valuable and are accessible to everyone. Some states will require a CCE and a PI license for investigative work. Texas and one of the Carolinas currently require this.
Wages vary greatly. A junior investigator can make anywhere from $35,000 to $50,000 depending on location and skill. A senior investigator can make anywhere form $70,000 to $150,000 due to various factors. These are private sector numbers. If you are an agent, you are subject to various government payscales.
Forensics skills are pretty universal, especially among North America and Europe. Job Security is quite good, even in this economy. Clearance is not require unless you are doing government work.
* Pen Tester:
In my experience CISSP is a good cert to have. It's famous and opens doors. The SANS certs are also fairly well known and can get you in the door. Obviously, experience counts here as well.
There are many folks doing that simply run a Qualys or Retina scan and call it a pen test. This market is fairly competitive and consulting hourly rates are much lower than in forensics. I am guessing that the job security here is not a good as in forensics. Very often, you don't have a choice but to hire a forensic investigator. Courts require a 3rd party neutral investigator in most cases. Forensics is responsive and often mandatory. Pen Testing is preventative and in many execs' view quite optional.
Salaries vary gain. I am not sure what the average numbers are, since I haven't participated in hiring a pen tester. My company primarily focuses on forensics and we do pen testing and audit much more rarely.
Clearance is again subject to who you are working for. Since computer systems are quite uniform and similar tools are used throughout, I can't imagine that it wouldn't be fairly easy to relocate to another country.
* Auditing / Analyst Lead:
CISA certification is pretty valuable here, as well as some accounting experience. You are often working for internal audit departments. Financial institutions have these guys on staff. Financial institutions are struggling now and I can't imagine that the Audit Industry is not hit as well.
I am not sure of the salaries here as well. I know too many people that have gotten laid off and have taken much lesser salaries here.
I believe this is one area where transitioning to another country would be more difficult since the regulatory requirements vary from country to country. The EU has standardized some of it, but you would have to still play catch up if you relocate.
I can't comment on CISO, since I am not at that stage of my career
Cyber Warefare job sounds quite sexy and should make you popular with the ladies. Ok maybe not.