Hello!
First of all I would like to say welcome to MWO.
First I'll start with matchmaking:
Every player in MWO is graded into an Elo ranking system. This number is hidden, basically to prevent epeen/bragging/bullying type behavior (In fact you have 4 Elo ranks - one for each weight class - light/medium/heavy/assault).
Now when you first start, it puts you into the middle rank and you'll need to play a few matches for it find your correct skill level. The more matches you play, the more accurate the ranking (theoretically).
So just hang in there, the game is notoriously tough on new players.
As for ping:
Correct, there are no local servers. Personally I live in Australia, which gives me a high ping of around 300ms. Certainly for most games of this type a ping of this magnitude would be most unplayable, but luckily MWO uses a few cheeky technologies (HSR - Host State Rewind) to try and make it at least bearable.
I won't go into the details of how it works and I will say it isn't perfect - however it is better than nothing. Also because the gameplay is actually quite slow and it's a war of attrition, ping isn't as imporant as it is in other shooters or melee games. I used to play a lot of Mount & Blade Warband, and if you didn't have under 60ms you were screwed basically. Playing MWO most of the time I don't even realise I have a ping.
Movement:
I'm not sure which throttle mode you are using - there are two (there is a "Throttle Decay" check box in the settings menu):
When the box is checked: You have to hold down the forwards key to move (like a regular shooting game). When you let go you will stop.
Box Unchecked (Recommended): It works like a throttle - pressing forwards will increase the throttle, backwards will decrease the throttle (Negative throttle for reverse). This allows you to "Cruise" at lower speeds than max. Also remember that pressing 'x' will bring you to a full stop (by setting your throttle to zero).
There is a movement tutorial you can do if you are unsure. Try practising in the proving grounds if you need to.
The centurion:
As soon as you win 5 matches (doesn't have to be in a row) you will automatically get your centurion. Although I'm pretty sure the offer is going to end soon.
"Clans"
This is a tough on to explain, because in Battletech (Mechwarrior) lore there is actually a faction called "The Clans" or "Clanners" - Therefore in order to avoid confusion organised groups of players aren't referred to as "Clans" but are in fact called "Units".
Many upon many Units exist in MWO. Some are affiliated with factions. Some are independant. Some are competitive. Some are casual. Most (If not all) communicate using a free 3rd party voice com software called Teamspeak 3. This is often why you will not see people typing communications, because its much easier to talk on a mic than it is to type.
Groups of players are, however, limited to dropping in groups of 4 players maximum.
Go to the recruitment section of the forum if you wish to find a unit to join - it's highly recommended.
http://www.nogutsnogalaxy.net/ also hosts a public Teamspeak 3 server that anyone can go on.
Being a Marik player, I use:
http://housemarik.enjin.com/ - All players are welcome
MWO is Hard
MWO is a hard game to master. I'd say it took me 50-100 matches to understand what was happening. Maybe another 200 after that to really feel like I had the hang of it.
Practice is the only way to get better unfortunately - But don't let this deter you. Stick with it. It's a fun game and very rewarding when you get there.
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There are many guides and advice sections in the forums.
Definitely recommended is the site:
http://mwo.smurfy-net.de/
It's a mechlab that lets you tinker with ideas, without having to spend hard earned c-bills making mistakes.
Also feel free to ask for help, most people on the forums like to help newbies get up to speed.
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Nice to see you around mate
Hope the advice helps.