Personally, I avoided spending diamonds on resources and saved them. The best way to earn diamonds without external means is to make sure you log in each and every day, even if it's only for a few seconds. You get one free diamond each day if you log in. If you always stay logged in and never log out, you lose those diamonds.
Some people more experienced than me could give you a better advice on what is really worth spending diamonds on. I used mine on heroes at 80 diamonds when they are available. A good way to get resources at your level is to look around you for faded cities and look at the ones ran by Neutrals (noCommander). Look for the ones below 10k, even 5k ones can give a really good output. Build some carts and go visit these towns, be careful and look closely at the combat log.
Small cities will have the advantage to have smaller groups of marauders which will be easy to kill for your small army. At your level, even getting 2-3k of each resources that way is a positive outcome. Be patient and don't try to go too fast, and be aware that you might lose your army more than once. I lost my entire army in the rob a city part of the tutorial, and a few times after.
About the wolves, they spawn at one of the gates.
