Most likely, u wo not see any effect at when u first start taking it. It takes a while to get the dose right, & most likely u will start off with a dose that is lower than what will end up having a theraputic effect for u because ur doctor will want to see how u tolerate it & get a sense of how sensitive to it u will be. I've been told it can take up to a month to get the full effect of the medication, although I would say that u will probably notice some improvement sooner than that.
Since Strattera is not a stimulant, it does not keep u up at night. Actually, it often has the opposite effect - one of the common side effects is drowsiness. The pills r time released so the medication stays in ur system for a full 24 hours. When the medication causes excessive drowsiness, doctors will often have their patients take their pill before bed rather than in the morning. So the point is that u will be fine before u take it in the morning because u will still have enough from ur last dose.
Strattera was originally tested as an antidepressant, & it did not end up working to treat depression, & it turned out that it did work for ADHD. But the point is that it is more like an antidepressant than the stimulants traditionally used to treat ADHD. Stimulants have an effect that is almost immediate, & works well with a single dose, because they're basically like super-charged caffine. They actually activiate parts of the fight-or-flight response to stress (specifically, the parts involved in alertness), & increase norephinephrine & epinephrine (adrenaline) levels only as long as the drug is actually in ur system (a few hours). Strattera, on the other hand, works by holding ur norepinephrine level pretty constant at a higher level on a long-term basis. It works by preventing reuptake of norepinephrine in the brain so that over time, levels increase. It is a lot like how certain types of antidepressants work, except it is acting of a different neurotransmitter.
As far as I know, you're not likely to become dependent on Strattera, although for it to work properly u do need to take it regularly. It should not change ur personality appart from improving attention & reducing impulsivity.
That said, these r all perfectly legitimate questions to ask ur doctor. Hopefully he or she knows quite a bit more about this than I do, & u should not agree to take any medication until ur doctor has answered all the questions u have about it.