RE: I would like to get the placeholder text a different colour as mentioned
?See https://blog.teamtreehouse.com/the-css3-placeholder-pseudo-element – that is best explanation I can find on how to style placeholder text.
RE: ??how to get the bottom two questions on the left side to be equally spaced like the other ones, they are currently too far away from the rest of the questions.
Sorry I had a look at your form. The approach you have used is very cumbersome and difficult to style. It would take me far too long to deal with the issues on your form.
But I can point you in the right direction where you can learn how to do it yourself.
Use Firebug or Chrome Dev Tools to examine the HTML and CSS of your CF7 form in detail. Once you understand how the HTML and CSS is configured in your CF7 form, you should be able to see the CSS changes you need to change the appearance of the form to suit your requirements.