I thought I'd made a reply here a couple of weeks ago, but I've been having lots of trouble with my computer and didn't get it posted correctly. (I changed by ISP, lost contact for several days with no end of trouble... and now my new wireless mouse is erratic. Unrelated, I know, but still. Grrrrrrrr)
So anyway, Oristar, if you have access to Microsoft WORD, it has a great outlining system. You should check it out, if you haven't done so. It is a little goosey (hard to control & flighty) but once you get used to it, quite nice. As to an outlining system being "Harvard" or not... <shrug>... outlining is typically not taught with that name, here in the states. I've looked around though, and the kind of outlining I learned in school is considered "Harvard" style. I've found a website that explains the three kinds of outlining: Diamond, Harvard, and Legal...
here.
I also believe it is best to tab in for each level of in an outline. Unfortunately, a2k, which is in all other respects perfect

, doesn't allow tabbing, so I can't show that to you. Anyway, increasing the margin indent with each level is very helpful. It is also good to add an extra line between the major headings. My recollection is you start with a Roman Numeral -- Main headings are I, II, III, IV, V.
The next level down are upper-case Alpha --A, B, C, D, E.
The following level is an arabic numeral -- 1, 2, 3, 4, 5.
Then fourth level is a lower-case Alpha -- a, b, c, d, e.
If you need to go to a fifth level, it would be an arabic numeral followed by a right parens -- 1), 2), 3), 4), 5) (all the previous levels should have ended with a period, as in: I., II., A., etc.)
If you have an outline which needs a sixth level (ugh -- way too complicated!) you'd go to a lower-case Roman numeral -- i), ii), iii), iv).
Somebody, somewhere, should be sure and mention that no outline should have a single sub-heading... ie. don't have an "a." unless you have a "b.".
You are exactly right that if you have a "2." and a "3.) you must have a "1."!! Good eye, O.
Outlines are very handy in describing information in a report. They are also handy as "working outlines" while writing, since they'll help you to see where you're missing information, or not leveling things properly. Other than that, they are a pain in the patoot.