I agree that number 7 is the best of the bunch. It still looks like the back of the bowl isn't as well-focused as the front, though.
There are a lot of variables, and it's easy to make one change and cancel another. For the type of photos you're doing, here are some basic thoughts. Sorry if some of it is too simplified, but I'll try to keep things in layman's terms for everyone's benefit.
Let's forget about ISO and exposure compensation for now...we'll get to those in a minute.
Two primary things control how the picture comes out: How big the hole in the lens is (the aperture) and how long the hole is kept open (the shutter speed).
The bigger the hole, and the longer you leave it open, the lighter the picture will be. Conversely, a little hole left open for only a brief time will result in a dark picture.
Shutter speeds are pretty self-apparent. A 1/60 of a second speed will mean the hole is open less time than a 1/30 of a second speed. So the smaller the fraction, the darker the pic will be.
Apertures are a bit less intuitive. A small aperture setting (or f/stop) means a big hole, and a larger number means a smaller hole. So the higher f/stop numbers equal darker pics.
These two things work hand in hand, but can also cancel each other out. A big hole left open for a short time will be about like a small hole left open for a long time. Both pics will look similar. In general, if you want lighter pics, you either leave the hole open longer, use a bigger hole in the lens, or both. In other words, for a lighter pic, you need to slow down the shutter speed, or use a lower f/stop number, or both.
Next, to get both the front and back of the bowl in focus, you need more 'depth of field'. As it turns out, a small hole tends to have a bigger depth of field than a big hole. In other words, a setting of f/22 might have everything in focus from 4 to 6 feet away from the lens, but a setting of f/2 might only focus from 4 feet to 4 feet, two inches. (These are not real numbers, but just used for illustration.) The trick to getting a lot of depth of field is to use as high of f/stop possible, slowing down the shutter speed enough to keep the picture from being too dark. For some real world numbers, the knife pics I posted a while ago were shot at f/29, with a 1 second shutter speed. And I still ended up lightening them a tad with Photoshop afterward. I could have use f/22 at about 1/2 second and gotten about the same results brightness-wise, but with less depth of field.
There is a distinct ratio between f/stops and shutter speeds, and a fair amount of math and science behind it. Lots of info on the web to go to sleep by. Here's one I found:
http://www.uscoles.com/fstop.htm
The ISO originally referred to how fast film reacts to light, The higher ISO numbers react quickly, and the lower numbers are slower. With no other changes, a pic taken with ISO 1600 film would be lighter than one taken with ISO 200 film. But...it'll be grainier, too. ISO 1600 is great for picture of fast-moving objects or people. ISO 200 (or less) is great for still life pictures and portraits. In digital cameras, the ISO is more of a sliding scale across which the f/stop and shutter speed are applied. A higher ISO setting will result in a lighter, but grainier picture. For still life pics like you and I take, we want less graininess, and don't really care how fast it is, so the lower ISO numbers are better.
Then there's exposure compensation. That's another fancy way of saying adjusting the lightness or darkness of the picture. I don't know if digital cameras do it mechanically by tweaking the f/stop and/or shutter speed, or if they do it electronically. Either way, just think of it as another way to lighten or darken a picture. The positive numbers will make a lighter pic and the negative numbers will give you a darker pic.
My recommendation would be to stick with an ISO setting of 200 (or less), and leave the exposure compensation at 0 until you get the two main variables (f/stop and shutter speed) dialed in to the range that results in pictures you like. Start with your highest f/stop number and adjust the shutter speed down until the pics are light enough. That should give you good depth of field. Then, if need be, you can tweak the exposure compensation a bit on individual pics as you see fit to lighten or darken things a bit. But first, get a feel for the other two variables. Like Jeff said as I was typing this...experimentation is your friend.
That's my (way over) two cents...