5. Can I change the FONT of the header (without using css)

If you have purchased the custom design upgrade, you can change the font for headers from the Appearance → Custom Design → Fonts page.

4. I love how my horizontally repeated gradient background works! looks cool! But it seems to be darkening the area underneath the 2 header lines. Can i change this so that the header has no opaqueness. Or is it in fact just an optical illusion?

The background for the main content area is currently setup with 88% opacity:

#wrapper {
  background: rgba(255, 255, 255, 0.88);
}

You can override that and make it white instead using CSS like this:

#wrapper {
  background: white;
}

3. "Text widget Designer worksheet" I am changing the font=size="7" but nothing is happening (I want it larger than at present to match other widget headers.

I looked in the text widget and I see this code for the heading:
<font size="6">Designer Worksheets</font>

<font> is an outdated tag. I would recommend using <p> or <h2> instead.

You can style the tag inline by adding style="font-size=2em;" to it instead. Or you can make it match the other sidebar heading styles by using the h3 tag instead and there is already styling built in for that.

2. flickr widget: can I LEFT-align the images? I think they are centred at the moment but centred on the column which does not look good.

The images in the Flickr widget are currently centered. You can left align them by unsetting the auto margin:

.widget #flickr_badge_wrapper img {
  margin: 0;
}

1. Facebook Widget: seems to have a LOT of space around it. Particularly underneath. I appreciate I have chosen *NOT* to display some of the widget's optional text but I would have expected the space to be freed up by so doing.

You can adjust the height of the Facebook widget manually like this:

.widget_facebook_likebox iframe {
  height: 70px !important;
}

I'm fiddling with the right hand bar but am getting a few, mostly aesthetic, problems. Any help on the following appreciated. Please note that I DO HAVE the CSS upgrade but am not using it yet with this theme. I want to try to do as much as possible beforehand:

1. Facebook Widget: seems to have a LOT of space around it. Particularly underneath. I appreciate I have chosen *NOT* to display some of the widget's optional text but I would have expected the space to be freed up by so doing.
2. flickr widget: can I LEFT-align the images? I think they are centred at the moment but centred on the column which does not look good.
3. "Text widget Designer worksheet" I am changing the font=size="7" but nothing is happening (I want it larger than at present to match other widget headers.
4. I love how my horizontally repeated gradient background works! looks cool! But it seems to be darkening the area underneath the 2 header lines. Can i change this so that the header has no opaqueness. Or is it in fact just an optical illusion?
5. Can I change the FONT of the header (without using css)