1) The quality of other players doesn't improve, you're just as likely to see almost all your team going one direction leaving the other team to come down the other flank. - This is the thing that annoys me about tomatoes. If you are that bad at the game, please stop playing before you get to top tier!
2) You'll get accused of being a base camping bot if you notice the above happening and being in a Centurion with weak hull armour, you get hull down near your cap to lay hurt down on the enemy team to hold them off. - I tend to find that I hold off one side on my own for a while (if I happen to be in a well armoured heavy), only to find the other side have all gone and died, doing nothing...
3) There are still tomatoes in tier 10 games (who am I to talk, I was orange until this weekend ) - See above.
4) It's not too hard to be in the top 1/3 of the team for XP earnt in a tier 8 tank in a tier 10 game (those juicy tier 10 tanks give you lots of XP). True
5) If you can't pen a tank keep it spotted and a big TD will do the job for you. Good shout. Unfortunately a lot of players don't keep things spotted, very frustrating when playing artillery.
6) Given the choice most players would rather shoot the lightly armoured tier 8 than a tier 10. I do this as it removes the lighter armoured tank's gun from the game quicker.
7) If you have a brain fart and die without doing much, even with a premium account you can still lose credits. As long as you don't do this too often you should be fine though.
8) The 20pdr is a good gun however don't expect laser guided surgical strikes, it still misses, some of my early frustration was expecting too much of it. Happens with all guns I'm afraid, though I do find it pretty good overall.