Dave,
You're 100% correct on at least part of that. The intent was, indeed, for the Senate to be the sedate, rational and experienced half of the legislative branch, and the House to be the "in touch with the people" wild and wooly half. I'm not sure, though, if the intent was for Senators to be career politicians. Could be. It used to be that they were appointed by state governments, rather then elected, so you could be right on that score.
Russ, NCNE