Yes. A person can have one manic stage in their lives and crash to depression and stay there, to a lesser or great degree, for years. Check out the difference between Bipolar 1 and Bipolar 2 on a medical website (like WebMD.com)..or on Wikipedia.

For me personally, it isn't a quick switch. It normally lasts for days... or longer.

If I understand your question correctly, yes. It is possible to cycle from mania to depression quickly, or it could take months or even years. you could stay in one stage for a long time before switching.

Yes, being bipolar there are no standards as to how you will behave as it can be different from person to person. The best thing to do is seek medical advice from a professional. Tell them your symptoms not what you may think that it is. Let them come to their own conclusions about your mental health. I have found that doctors are very busy and may only check you for one thing and either tell you that you are or are not and will not search any further into it without returning several times.

Yes. A manic episode is characterized by period of time where an elevated, expansive or notably irritable mood is present, lasting for at least one week. These feelings must be sufficiently severe to cause difficulty or impairment in occupational, social, educational or other important functioning and can not be better explained by a mixed episode. Symptoms also can not be the result of substance use or abuse (e.g., alcohol, drugs, medications) or caused by a general medical condition. Three or more of the following symptoms must be present: * Inflated self-esteem or grandiosity * Decreased need for sleep (e.g., one feels rested after only 3 hours of sleep) * More talkative than usual or pressure to keep talking * Flight of ideas or subjective experience that thoughts are racing * Attention is easily drawn to unimportant or irrelevant items * Increase in goal-directed activity (either socially, at work or school, or sexually) or psychomotor agitation * Excessive involvement in pleasurable activities that have a high potential for painful consequences (e.g., engaging in unrestrained buying sprees, sexual indiscretions, or foolish business investments) Psychomotor agitation: Depression, which affects people of all ages, income, race, and cultures, is a disturbance of mood and is characterized by a loss of interest or pleasure in normal everyday activities. People who are depressed may feel "down in the dumps" for weeks, months, or even years at a time. in the same 2 weeks, the patient has had 5 or more of the following symptoms, which are a definite change from usual functioning. Either depressed mood or decreased interest or pleasure must be one of the five: Mood. For most of nearly every day, the patient reports depressed mood or appears depressed to others. Interests. For most of nearly every day, interest or pleasure is markedly decreased in nearly all activities (noted by the patient or by others). Eating and weight. Although not dieting, there is a marked loss or gain of weight (such as five percent in one month) or appetite is markedly decreased or increased nearly every day. Sleep. Nearly every day the patient sleeps excessively or not enough. Motor activity. Nearly every day others can see that the patient's activity is agitated or retarded. Fatigue. Nearly every day there is fatigue or loss of energy. Self-worth. Nearly every day the patient feels worthless or inappropriately guilty. These feelings are not just about being sick; they may be delusional. Concentration. Noted by the patient or by others, nearly every day the patient is indecisive or has trouble thinking or concentrating. Death. The patient has had repeated thoughts about death (other than the fear of dying), suicide (with or without a plan) or has made a suicide attempt.