Need Your Help PLEASE!

So I’ve only been playing for about a week now and just now coming across these forums and seeing the posts from people saying “wish I would’ve known” etc. So I had a couple of questions if anyone can help:
-even though I’ve only been playing a week, I am assuming I can’t do the apprentice thing because I am at level 42 unfortunately, correct?
-I saw a mention in one of the discussions about difficulty levels, and I am not seeing how to change those, identify what difficulty level doing or more info about them.
-as I was getting very confused about different types of currency (can’t think of a better word, but stones, silver, gems, energy etc) and seeing as I did already spend the initial currency we got, was wondering if you could point me in the right direction in what you would save up for first and maybe what order you buy things in for that currency, etc. I get very instant gratificationish and the first category that pops up that needs a certain currency especially when I am getting defeated in levels, I don’t even think about saving it but just trying to beat it. So I was just wondering what I need to be saving it for.

For example:

  • Gems: Save until can get a 3+ star mage or higher (Arch Mage maybe)
    -Energy: Spend on or save for ______.

I attached images of the heroes and info and will try and add a couple more pics for info…THANK YOU SO MUCH IN ADVANCE…I really wish would have done apprenticeship. :frowning: