I am a Software Engineer with a Bachelors in Information Systems from the Engineering School of USF Tampa, FL (go Bulls!).
I got into this line of work when I took my first FORTRAN class on the way to becoming an Electrical Engineer. I discovered that I liked programming computers more than I liked designing them. I actually started working in the field before I graduated, doing graveyard shift computer operations at a hospital. Then when I had my AA (This was 1975, there weren't many computer specific 4 year degrees), they offered me a spot on days doing COBOL programming. Over the next 25 or so years I held various programmer / analyst positions and finished my 4 year degree. My current position is Software Consulting / Business Analysis. I provide a range of services from Data Conversion through completed applications. See my site at click here for my consulting company
For most Software Engineering these days, the minimum is a BS. Other Engineering disciplines (Mechanical, Electrical, Chemical) also require BS as a minimum.
The thing I like most about my work is starting with a blank pad of paper and designing an application from the ground up, then seeing it through to completion. A close second is training. I love one on one and small group (< 20) training. The feeling of actually helping someone get it
is hard to match
. The thing I like least is bug fixes / maintenance (mostly because it is done under the gun and is usually because of a design screwup that I was at least partially responsible for).
To learn more about Mechanical Engineering I would suggest that you continue your reading in the field as well as keeping up with the professional journals. I know in the EE field IEEE has a journal. For Mechanical maybe ASME? You should also consider a Masters along the way. (I would suggest you get the Masters while working somewhere. I think you get more out of graduate work if you have some real world experience).
When I was doing my Engineering degree, we had a class called "Engineering Orientation" that brought in local Engineers to discuss their work and cover the same types of things as your four questions.
Feel free to email / PM me if you need more.