To show and hide rulers:
On the toolbar at the top, click on View then select (or deselect) "Ruler"
The setting will remain that way until you change it in the future.
As far as the margins, if I understand correctly, you basically want to change the margins and set those changes to be the default settings. In that case do the following:
Double-click on the ruler and the settings box for margins will pop up. There you can set the margins to whatever you want. Then, at the bottom of that box, click on the "Default" button, to make those new settings become the default settings. Click "yes" to confirm your changes.
I assume you also know that for quick margin adjustments, you can place your mouse on the ruler, where the white part meets the grey part and the mouse turns to a two-way arrow. Click and drag to adjust. You can bring up that margins-settings box to set those values as the default.
Note that this will apply the changes to whatever template you are working on, which most likely will be the "normal" template. But if for example you are working off of a "business letter" template (just to name one example) then the changes will affect future documents based on that template only. The "normal" template is the one automatically used when you simply open MS Word.
***********
EDITED: Hmm, I just re-read your post, and I think I answered more than what you were asking, but oh well, I'll leave it anyway.
