although I've had two tonic colonic seizures and a questionable atonic, what else might I be aware of?
There many seizure types, and they are classified in inconsistent ways (just to make it confusing.) You can get a pretty good rundown from wikipedia:
http://en.wikipedia.org/wiki/Seizure_types
The ones that are often hardest to notice and/or diagnose are the ones that don't tend to produce dramatic or highly-visible symptoms. These are called Absences, and Partial Seizures.
Absences are a kind of generalized seizure (meaning that the whole brain is involved), but they are so brief (a few seconds) that the person doesn't realize that a seizure has occurred. To the observer it may seem that the person is daydreaming or inattentive. It's as if the on/off switch in the brain is flipped very quickly.
Partial seizures involve only "part" of the brain. They are also called "focal" seizures since they start in a specific "focused" area. With "simple partials" the person remains fully conscious and aware and has a memory of the event. Simple partials can take a wide variety of forms, mostly involving some kind of sensory disturbance -- things like perceptual distortions, sensations of fear/nausea, phantom smells/sounds, etc. If a simple partial progresses into a seizure involving full loss of consciousness, then it is called an "aura".
"Complex Partials" are partial seizures that have spread to include wider area of the brain. The person is still conscious, but their awareness is impaired. The person may show "automatic' behaviors -- things like smacking the lips, or picking with their hands. They may have trouble speaking. They may say or do strange things. Think of it as a bit like sleepwalking.
is it usual to have various types of seizures?
I'm not sure if there's a "usual" in epilepsy.

In my case, I've never had absences or partial seizures -- I just launch right into a tonic-clonic. Other people might have only myoclonic seizures (which consist of jerks and twitches). Others might start out with one kind of seizure (partials) and over time have them progress into a different kind (tonic-clonics). I think that different prognoses have to do with a variety of factors including the primary cause of the seizures (e.g. genetic/brain trauma/lesions/vascular problems/unknown), the area of the brain involved, the age of the person, how quickly the seizures are diagnosed and treated and how well they respond to treatment. There can be secondary triggers and lifestyle factors that can play a role as well.