You are getting way ahead of yourself. Concrentrate on getting hired first. Education is important. Most important thing if/when you are appointed as a police officer is do a good job. As you are aware of you have years of paying your dues. We get this question often so check the forums.

Have you made application and have you been offered a law enforcement position? If your response is no then trust me you are getting way ahead of yourself. even with military service and education there is no guarantee you will be appointed as a police officer. Having dreams and goals are fine.

Assuning yu ae hired someplace as a LEO and want to work towards SWAT, I would recommend becoming a paramedic, there are not a lot of people qualified to be SWAT medics and so people wo can do that have a foot up, realize that to be a paramedic is probably 2 years of classes and annual training gereater that most LEO's are required to do.  Don't even know if SWAT medic is your cup of tea.

 To address your specific questions

Would I have a better chance working for a metro force or a small one?

Larger municipal departments or county, state and federal agencies are more likely to have their own  SWAT/Tac Teams.  Smaller agencies do not have the manpower to support such a specialized unit (although some smaller agencies forge relationships with other small agencies to form joint teams).

- Would becoming a sherrif or State Trooper effect my SWAT aspirations?

See above

- Are there any courses that I could take outside of LEO training that would help?

In most instances SWAT/Tac training would be provided by the Team once you were accepted.  I would definitely recommend being in top physical shape as a start.  Beyond that, once you do get hired by an agency and get through the basic academy I would recommend that you

check with your local academy as far as what In-Service training they have available and apply for any courses that would enhance your tactical background such as Interview/Interrogation, Unarmed Self Defense, Building Clearing, Tactical handgun/shotgun/MG shooting courses, EMT training. (Don't count on your military training to get you by.  There are many differences in the types of training involved).

 Are there certain duties or jobs that I should work towards or volunteer for that would help propel me towards SWAT?

Not really.  The main thing is to be the BEST officer that you can be and be consistant in doing the duties assigned to you.  You mention waiting 10 yearts to apply for Teams but many Teams will accept members upon completion of 3 years in Patrol (as long as they are worthy of acceptance, just because you apply it doesn't mean that you will be accepted). In your first 3 years you will not be eligible for any special units so your reference to "certain duties" makes that a moot point.

 - Basically anything that would help make me the best candidate possible for SWAT is what I am looking for

 You need to make yourself sellable to the Team, to make yourself an individual that would be an asset to the Team.  You need to show them, over your first 3 years, that you are focused, dedicated, hardworking, not a clockwatcher, and that you are a team player (Hot Heads and SWAT Wannabees need not apply).

A few things to think about.........

When you get hired DO NOT run around telling everyone that you want SWAT (it makes you look immature and too much of a Wannabee)

During your first 3 years get to know some of the guys on Teams, gradually start working out where they work out, talk about your military experiences (many of them will be ex-military anyway), and let them get to know you as a rational, dependable and intelligent individual.

Remember that Teams are made up of multiple levels of responsibiliy and you may not get your first choice position when you first join them.  Some of the responsibilities include Negotiators, Snipers, Entry Team, Extraction Team, Perimeter Security, Command Post, Armored Vehicle Operator...etc