Question 1: 

           for (int pos = 0; pos < 2 * k; pos += 2) {
               words.add(pos, words.get(pos));
           }

Question 2:

           int pos = 0;
           while (pos < words.size()) {
               String word = words.get(pos);
               if (word.equals("hello")) {
                   words.remove(pos);
               } else {
                   pos++;
               }
           }

Question 1: 
        public Object remove(int pos) {
            // check for bad pos
            if (pos < 0 || pos >= numItems) {
                throw new IndexOutOfBoundsException();
            }

            // get the item to be removed from pos
            Object ob = items[pos];

            // move items over to fill removed pos
            for (int k = pos; k < numItems - 1; k++) {
                items[k] = items[k + 1];
            }

            // decrease the number of items
            numItems--;

            // return the removed item
            return ob;
        }

        public Object get(int pos) {
            // check for bad pos
            if (pos < 0 || pos >= numItems) {
                throw new IndexOutOfBoundsException();
            }

            // return the item at pos
            return items[pos];
        }