what additional payment does a player receive on top of his club's wages for playing in an international?

it depends on the country and what tournament. for example: for friendlies, countries will usually pay their players for their services from a pot based on what revenues they will make on ticket sales, advertisement sales, television rights, etc.

for tournaments, each country gets an amount for participating and additional amounts for each round they survive - countries will generally pay their players a portion of the revenues they receive. often countries will give performance bonuses for rounds survived, games won, goals scored, clean sheets kept - just as clubs would.

as stated above, the england national team (players) have collectively decided to donate their earnings for national team duty to charity.

in england they give all there money from the internatinol match to charity