You will need to follow the steps below to convert to Pro:
Your theme will remain as it is unless you use the Header/Footer functionalities of the Pro theme.
I would not say it is for developers but for more savvy guys which prefer to have more options to play with and fine tune their website.
I suggest that you check these for more information:
Also, another good point is to check the Pro section of our KB:
Check the articles of the Pro which contain videos and shows the features which will give you a better idea if Pro is something you would like to use or not.
And at last a series of Youtube tutorials that may interest you:
Thank you for using our products and your interest in our new Pro software.