Glad that you're interested in playing BD! Annonymu5 has already answered some things, but just to clarify a bit as well
1. The game is by no means pay to win (some may argue). The player considered the "best" doesn't spend a dime and has completely dominated eras without boosting (Senatus is that player, who's guide you were referred to)
2. The game itself doesn't truly have that much you need to learn. It will SEEM overbearing at first. Simply because it's lots of little things. But after an era or 2, those things become second nature (what chassis type kills what, armor damage range units, what gives score, etc). Just take your time to learn the small pieces and then you'll learn there's really not a lot. The biggest thing to this game however is activity. The more time you can put in, the better. Often players on BD become like family. You'll be put in chats with your teammates and you'll end up talking daily for months at a time to pass the time.
3. As stated, good players will hit you. It's simply the nature of the game here. Everyone is vying for top ranks and you get there by dominating others. At first, this may seem hard to overcome. After you get the basics down though, you realize it's actually very easy to overcome. It really comes down to working with your teammates. And even great teams fail. Do keep that in mind. So do not be discouraged if you lose a war to a great team. Once again, simply the nature of the game.
If you ever have questions please feel free to reach out to myself or the community in general. We're always willing to help. You can also look towards the BDA (BattleDawn Academy) which is our mentor group. http://community.tacticsoft.net/t/battledawn-academy-formerly-adopt-a-newb-centre/429
Good luck and hope to see you and your friends enjoying the game!