The first query is good -- you see how there's no filesort, and the key isn't NULL?
The second query is bad for two reasons: first, there's no index on the members (table scan = ALL)... second, you're using a dependent subquery, which si executed once for EVERY matching row of members -- or ~2600 times! Could you explain what you're trying to query?
For the 3rd one you still have no index usage -- add an index on friendID for the members_detailed table, and add a composite index for ( theirs, yours ) to added.
Also, your queries would really benefit from table aliases and column prefixes.