Help with updating a page for work

Hi, I i have recently started in a new job and part of my role is updating the shops web page. it has been set up by someone else no longer managing it and i am trying to figure out where they left off.
my first question...
how can i find out which version of opencart is being used and is it correct i would have to go through updates one by one and question two is the only way to change colours/layout by downloading a ready made theme?
I will certainly have more questions in the future but any tips would be brilliant!
thanks

this is the code of the ROOT + ADMIN index.php, telling you, wich version you use.
And for following Questions, I advise you, to first always check GOOGLE first,
a lot of usefull Information can be found in & outside this Place here as well, and
the OC Forum search Engine is rather limited in in function and use.
You won't be frustrated this way, because this is less a Place for Newbie's here,
asking questions, answerred uncounted times already before, as you will find out...
Good Luck !
Ernie