dorareever -
Before lessons my upper range was weak and squeaky - so I never used it because it was so appalling compared to the low range I had got comfortable with.
On my first lesson I was asked to "siren" up and down so that Tania could ascertain the potential range. She assured me that no matter how sqeaky or weak the note was at that time - if I could get the note out then it was singable for me. Then it was a case of learning how to sing those notes - a good part of which was learning to "suck the note in" instead of "pushing it out", and learning that that higher notes need much less air expelled than the lower ones.
After a while I had about 3 really good quality notes somewhere in the middle of the soprano area. That quality (pure & ringing), once found, spreads across the range with time & practice.
Tania uses a lot of imagery in her teaching & so some of it only really makes sense to me after it is achieved.
There's tons to learn and it really fascinating and exciting - so I'd really really really recommend lessons with a classical teacher. If you can master the classical techniques then you have a lot of control over the voice and can sing better in whatever style takes your fancy. You have more options available to you on how to deliver the songs and how to use your voice in each situation to really express yourself - which is great fun if a bit bewildering at times.
And I had no plans to sing opera either - but I've changed my mind now..... I find its more fun to sing than it is to listen to.

As regards female voice changes over time - I'm told that the female voice doesn't reach its best until mid-forties. Yippee - I'm not too late then!!! (I also hear that a properly trained voice will last way into old age with little loss of quality)

Kris