Current Service

I'm looking at some options on my current service and have a couple of questions.
1.) How do I tell if my current service is 100 A or 200 A? It looks like there's 2 feeder lines coming in to 2 main breakers with 100 A on each. If this is 100 A, what's involved in upping it to 200 A (new feeder lines, panel, etc.)?
2.) There's no room for additional breakers in my panel. There's 2 breakers with 2 circuits wired in which I'd like to put on separate breakers and I'd like to add a couple of circuits. Do I have to put in a new panel, a sub panel or can I replace the existing breakers with 1/2" wide breakers and get more on the existing bus?

 

If your main breaker says 100A then you have 100A service. You can always add a subpanel, then move some circuits to the new subpanel. You may want to first do a load calculation and make sure 100A is enough for your house. Upgrading to 200A would involve a new main panel, all the wiring between the panel and the utility drop, and probably a new meter base.