There are 5 questions. The following contains two functions for traversing a binary tree:

struct Node
{
    char key;
    Node * left, * right;
};

void trv1(Node* root)
{
    std::queue<Node*> Q;
    Q.push(root);
    while (!Q.empty()) {
        Node* cur = Q.front();
        Q.pop();
        printf("%c", cur->key);
        if (cur->left) Q.push(cur->left);
        if (cur->right) Q.push(cur->right);
    }
}

void trv2(Node* root)
{
    std::stack<Node*> Q;
    Q.push(root);
    while (!Q.empty()) {
        Node* cur = Q.top();
        Q.pop();
        printf("%c", cur->key);
        if (cur->right) Q.push(cur->right);
        if (cur->left) Q.push(cur->left);
    }
}