Welcome to Celtic Heroes!
A Warrior is a great class to start out with, and a slightly tankier build is a great choice for a newer player who wants to save a bit of gold. As you move on in levels you may want to lean a little harder on the damage side of the class, for faster and easier leveling, but that point is still a bit farther down the road! For general Warrior advice you could check out the
Warrior subforum. A lot of the posts tend to aim towards endgame players, but there are some pretty helpful guides scattered throughout. Otherwise, feel free to make a new topic if you have a list of questions, and I'm sure our awesome forum users would be happy to give you some tips and tricks!
Around lower levels there do tend to be a bunch of people coming in and out of the game, a lot of people prefer to just dip in and out of MMOs at the start, until they either get hooked on the game or bored with it. Soloing is a great option in Celtic Heroes (especially for Warriors), but leveling with other people is fun too. The social aspect of Celtic Heroes is one of my personal favorite parts of the game, simply logging in and chatting with clan mates throughout the day. As you get a bit higher you will see players starting to stick around more. I'd also definitely recommend joining a clan if you can, I'm not sure about Mabon in particular, but there's usually a bunch of smaller clans throughout each server (don't worry about the endgame clans with all the high levels yet). It could be worth joining one just to chat with some other players more easily as you level up and share what you find in your adventures.
Yes, the Tavern was recently updated to be a Global area, which means that players from any server can enter it and they are all together at the same time (with players being marked by the #servername as you noticed). You can't trade with any players from other servers, but it's a great way to say hi to new people and hang out while you cook.
Prices are usually server-specific, and I'm not really familiar with Mabon's prices. 50g per Oat kind of sounds accurate, but I could be wrong. It also depends on how badly someone wants to buy it from you! If someone really wants it, they may pay more than it's worth. My advice is to see if anyone else is selling it, and see how much they sell it for. If you are having a hard time finding people to buy your Oats, you could try bumping the price down a bit. On the other hand, if you sell them all quickly, you may be able to ask a bit more.
If I'm completely misreading this and you are trying to buy Oats, then you'll just need to decide whether the Oats are worth 50g each. If you don't find anyone willing to sell for that price, pay more, whereas if they are all too happy to sell you their stash for that price, you may be able to get it for cheaper later on. Wheat and Oats aren't terribly hard to farm, so it may or may not be easy to find someone selling them.
If you have any questions about the game in general, feel free to post them here on the forums! We have plenty of experienced players here who would be happy to share some of their knowledge. You can also feel free to send a private message to any of us Forum Guides (with the
blue names) at any time and we'd be happy to help ya out with whatever we can!
Enjoy your time in Dal Riata!