Ron,
the fact that you had some problems with 7.1, may mean that you had a previous Netscape6 or 7 which installed the same way. Except that things are progressively worse. Unfortunately, the fact it was ok to install "on top" with 4.x is not forgotten, and Netscape and Mozilla from which NS is derived will let you carry on, and continue getting into trouble. This bugs me, but I know the ropes, but I was caught once not thinking, and I was burned.
As for the extras, as you found out they are not part of Netscape, but they seem to be. There are custom installs for that. It is supposed to be for the user's convenience, but, obviously they are not.
As for the profile, being so big, it seems that you may have saved all your mail for years, and possibly have huge a huge bookmarks.html file.
I decided to check my profile, and it weighs in at 22.3 Mb. My bookmarks file is 47 Kb. I assure you that dragging as much stuff as you do is not helpful.
You can also check, with Netscape closed , you profile, and delete the xul.mfl file, if larger than 3Mb.
And, of course, you can use other software, but, in all fairness, is it treated the same way as Netscape?
UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8a4) Gecko/20040927