If by the wording "implement" you need "install", and so you ask how it would be easy to install those add-ons, I just could say their README instructions in many cases are similar to the instructions provided for the free add-ons. Basically, they all are working by the same copy/paste principles: take the code here, paste it there etc. I suppose if other add-ons were possible for you to install, those premium add-ons will be easy to install as well.
Please note that we provide FREE service regarding premium add-ons installation. So even if you will have some difficulties, we could help you in solving them.
What do you mean by "free templates"? Do you mean skins?
If so, the old skins are temporarily removed from the site, because they are not compatible with the newest layout schema of miniBB.