Mal - Probably the best way to learn to play the game is watching tutorial videos. However I never did that until I was really far along in the game. Initially I think self-teaching yourself the various maps and learning how to best use the tanks you have in your garage is a good way to start. For me I wanted the German tanks (of course) so I started with the tank destroyers and heavy tanks. Once you get up to say tier 5 things start to change a lot. You are no longer in 'beginner' matches and a lot of the random events seem to go way down. That is not to say you can't still find lots of idiot players at higher tiers, there are just fewer of them.
Periscopes, Repair kits, and camouflage are definitely the best equipment purchases you can make. You can always easily move those between tanks and you never are locked in like you can be with items that require gold to remove them and use them on another tank.
Premium tanks are very fun and come completely ready to fight. No upgrades needed. You need a good crew of course and you if you do opt to buy a premium tank, but one that compliments your existing tanks. So if you are playing German heavy tanks for example you might want a Lowe. That way you can use your crew from say your Tiger in your Lowe. They can pretty easily be moved back and forth as needed.
As for money required to play, Luciano, you can play completely for free. I did that for a long time and enjoyed the game. Of course the more time you invest in the game the more likely you are to want to do something using gold. For me it was things like moving equipment, up-training crew members quickly, etc. That said there are a LOT of players who never use gold or premium tanks. Most of the things in the game that use to require gold, you can now buy with the equivalent silver credits that you earn in each battle. So for example where in the old days only gold users could use HEAT or APCR ammo, now you can simply opt to use the credits you earn for free in the game.
I however have spent a lot of money on this game. I look at it this way though. I use to buy a $50 PC game every 6 months or so. This game keeps changing and kept me interested for 2.5 years. So that means spending a bit on it here and there is okay for me. I didn't start off playing with that attitude though.