Franciscus, this has already been covered
here. (or see the posts below)
Tachyon, I believe that's hard coded, unfortunately. It would be nice to train troops in castles.
GetAssista, you can do that, but without the module system it isn't trivial. With the module system you'd just go in and change the tier 1-5 rewards and it would get set everywhere. Without it, you have to go into conversation.txt and edit them all. If all you care about is how much you get, first search for arena_training_melee_intro_reward to get to the right area. Then search for:
1 3 936748722493063468 360287970189639680
That will be followed directly by numbers - 5, 10, 25, 60, and 250. Those are the amounts that are actually given to you. If you want to make it say the right amount, go back to arena_training_melee_intro_reward and search for:
This is where it tells you how much you've won when its giving it to you, and will be the same series of numbers. And then if you want it to tell you the prizes correctly in the conversation when asking about prizes... Go back to arena_training_melee_intro_reward and look for the group of lines like this:
2133 2 72057594037927947 5
That's telling the reward for tier 1. Go through and set the 5, 10, 25, 60, and 250 in that series so that it will display correctly. THEN you go to arena_training_melee_explain_reward (the next dialog) and do the same there. These are both basically the same dialog, but one is called when you very first ask for the reward, and the second is called when you ask again later.
And for the village improvement build times, that's in menus.txt. Look for menu_center_improve. Heres an excerpt:
menu_center_improve 0 {s19}_As_the_party_member_with_the_highest_engineer_skill_({reg2}),_{reg3?you_reckon:{s3}_reckons}_that_building_the_{s4}_will_cost_you_{reg5}_denars_and_will_take_{reg6}_days. none 22 1 2 936748722493063459 144115188075856091 2133 2 1224979098644774912 72057594037927936 2320 2 4 0 2320 2 19 1 1 2 936748722493063457 1369094286720630792 2133 2 1224979098644774913 72057594037927936 2133 2 1224979098644774914 72057594037927937 2133 2 72057594037927938 1224979098644774913 2121 3 1224979098644774915 5 1224979098644774913 2107 2 1224979098644774912 1224979098644774915 2108 2 1224979098644774912 20 2123 3 1224979098644774916 1224979098644774912 100 2105 2 1224979098644774916 3 2133 2 72057594037927941 1224979098644774912 2133 2 72057594037927942 1224979098644774916 4 0 31 2 1224979098644774914 360287970189639680 2133 2 72057594037927939 1 5 0 2133 2 72057594037927939 0 2322 2 3 1224979098644774914 3 0 3
The red 100 is the amount it divides the cost of the improvement to get the time - so for every 100 denars of cost, it's a day. You could up this to 500 or 1000 to significantly decrease build times. The red 3 after that is the amount of days added after it has got the number from dividing - you could set this to 0 to directly knock 3 days off all the build times. While I'm here I might as well note that the blue 20's are the way engineering skill counts into things. It takes the first 20 minus engineering skill divided by the second 20. So the default is 10 engineering = 50% of the cost and time. You could change them both to 15 to make it 10 engineering give only 1/3 of the cost and time, or even 12 for 1/6 - just don't change it to 10 or less, or it'll be free improvements (which doesn't make much sense!).
