For 6, it's not at all difficult in it's simplest form. You just use a 3-column, 3-row table and set the BG graphic for the corner cells to be a pic of a rounded corner. The problem comes in matching the pics' colours to the table background - This can be hard as various browsers slightly disagree on how to render colours whereas the images are displayed as-is, but there's a simple trick to fix it: Make a 1x1 px image of the proper colour and set that as tiled background for the rest of the table.
Tada, rounded corners.
[Edit] Another thing: Ought to roll booking info and contact into one booking/contact link since they lead to the same place anyway. Different links to the same page are an annoyance for visitors, as they can end up thinking the site is hanging when in fact they just clicked over to the same page they were already on.
[Edit] Oh yeah, probably don't even need to tile the 1px background 'pic', it should stretch well enough. Not quite sure though, been a while since I did any web design.
[Edit] One more thing: Plan for visitors to have different resolutions from the one you run. This means defining such things as width values and the like (though generally not for pictures) as a % of screen width rather than a fixed pixel value, that way you keep your formatting under all resolutions.
This is mainly the case for simple sites such as yours though, for more complex sites where precise positioning of elements takes on far greater importance, there can sometimes be no choice but fixed values (HLP main site being a borderline example of this - scaling could not easily work with all those graphics having to align perfectly).
[Edit... again. I need to stop this soon] I should mention that it certainly is possible to do both nice graphics layout and dynamic scaling with resolution though. You just use fixed widths on the leftmost items and then tile a matching background to the right of those, which will then fill out the screen nicely while keeping the good looks. It's when you start needing to align pictures with background graphics or certain items on the page (such as the 'home' banner on HLP being the exact width of the news and highlights items combined) that the site starts to need fixed widths to keep looking top notch. Can fudge it to some extent, but it's rarely worth the effort.
On HLP for example, the home banner could taper off into black (or perhaps a repeatable star pattern) on the right side as it already does on the left, the top and bottom graphics could end in a uniform look that could then be tiled seperately, and finally the primary div and the news item could be made dynamic width while keeping the nav bar and highlights fixed width. Complicated and time consuming to get right, but could be done... just not worth it as it already looks great

Just an example for how it works if you want to do stuff like that.