You can do all of this with CSS, just read up on that a bit, its not really related to silverstripe. You shouldn't be adding borders onto the table, thats how it was done 10 years ago. I'd suggest giving your table an id such as <table id="contactinfo" cellpadding="0" cellspacing="0" border="0">
css styling forms to change the font-size/box widths/whatever is much the same.
For silverstripe forms in particular I'd start your form.css (yours looks empty at the moment?) file with the code from: