I notice some eras, admin put xtals on metal mines, and troops their, i believe this is good, as xtals will boost score so u dont have to boost, and troops will prevent the usual spam ppl send? is it possible to have more of these worlds?

As you wrote, there are some worlds where ADMINs put crystals on mines and garrisons. But for earning something you must give out something. So they put troops on them. While on some garrisons too they put troops.
For more information on garrisons please refer to this:http://wiki.battledawn.com/index.php?title=Relics,_Crystals,_Wreckages_and_Garrisons.
Check out the garrison part.

And on more these type of worlds, the settings are changed every era in CUSTOM WORLDS only. One such example is Earth3, Fantasy4 and Galaxy1.

also on mars 2 many times

It depends on the thing that either the world you are playing in is a custom world or not.