Radio buttons and Submit button style

Sure. Go to your "credit card type" field in the form editor, click on it then find the "CSS class name" field under the advanced tab. You can enter "gf_3_col" in the field then save the form. That should format your list into 3 equally spaced columns.

If you want to try the 1.5 beta version of the forms, there are other new "ready classes" that you can apply to do some advanced formatting.

http://www.gravityhelp.com/css-ready-classes-for-gravity-forms/

Now, a caveat. I see that you're using a Woo Theme and they've overwritten some of the default form styles - notably forcing all of the labels into a left label style layout. I see a couple of your checkboxes are aligned to the left under the main label which they wouldn't be if you were using the default, built-in "left label" form setting. If you have other styling issues related to that, you'll need to contact their support team to find out how to disable the overriding styles.

You can target the button with some simple CSS inheritance this way.

body .gform_wrapper .gform_footer input.button {background:red}

if you want it to apply to just one specific form, you can use the ID like this

body #gform_wrapper_8 .gform_footer input.button {background:red}