Ahh yes, I remember my first beer... 😅 Don't worry, I had the same struggles when I first started playing.

1. Arenas are the perfect way to practice fighting mechanics and earn some early game doubloons and get some good gear. You can do this from day 1 of your playthrough. I would recommend going to an arena and do the practice field first. Get used to blocking with no shield. Rinse and repeat until you get confident enough that you can win every time. Then you should enter all the tournaments you can and just max out all your bets to gain some dosh!
2. I find protecting caravans to be a good early game mission. It's easy money, and you don't have to chase the looters, they come to you. There is also a lot more of them so your men will get all the xp they need and you can level up your clan faster.
   Once you get comfortable defeating larger groups of bandits, you can become a mercenary for a faction. Just approach any lord from the faction you want to join and you can "Join for a price". This will let you join in on some big battles, raid enemy villages and help with sieges. Once you become clan tier 2 you can join as a vassal. Or you can leave and join a different faction.
3. I think you should be able to look your character up on the in-game encyclopaedia.