and just one little more question...
on my portfolio page, (page 3) the gallery grid has 3 columns, I want 4 columns. I have changed it 4 rows in the settings yet nothing happens. is this this a css thing? how do i change it?

Flying a bit by the seat of the pants on this. Try this. Change the width number to go wider or narrower.

.page-id-2 .post-content {
    float: right;
    width: 50.333em;
    overflow: visible;
}

To get rid of the date use:

.timestamp {display:none;}

If you want to get rid of it AND the comment bubble, use one of these. The behaviors are very different, so it depends on what you want to do. The first hides the content but the space it occupies is still used.

.post-info {visibility: hidden;}

or this that removes the content, thereby releasing the space it occupied

.post-info {display:none;}

This support document explains it more clearly .. http://en.support.wordpress.com/custom-design/editing-css/

.home #header {display:none;}

@melissa... The twenty twelve theme allows some setting of headers for certain pages. I do not know if it has the option for no header. Checkout this article to read more: http://en.support.wordpress.com/featured-images/. It did not look like you have the css upgrade. If you choose to test a css solution, you can use a similar css by identifying each of the page Id's where you don't want the header and put that into the css. For example, to eliminate the header on your about page, you would use this to preview it in the css:
.page-2-id .header-image{display:none;}

But before you do this, check out whether you can set the presence or absence of a header through your Dashboard, Appearance, Header settings.