To dismiss troops,
click shrine of odin
click in the town
click troops
The rest should be easy,
Alternatively, attack someone, or a clan member( temporarily left) to attack you, that way you get points and the option to heal or resurrect them, assuming you have enough infirmary space..
The troops eating food is only a problem if you have no food for upgrades.
There are ways round this ,and to increase your food production, of course you might already be maxed out.
You are right about the leagues, and how demoralising it can be,not to be able to hit check points.
The big clans use all kind of tactics to make life easier for them, one of which is poaching the better players from other clans, though it might,its not really to help those they recruit, as they suggest, its self interest .
I do not think you will find the stats that you are seeking, its all guesswork ,and not official.
You just might find its to your advantage to split your clan.