How to get every product's quantity in event observer json file?

Question

public function productDataToJson(Varien_Event_Observer $observer)
{
  $category = Mage::getModel('catalog/category');
  $tree = $category->getTreeModel();
  $tree->load();
  $ids = $tree->getCollection()->getAllIds();
  $jsonFilePath = Mage::getBaseDir().'/jsondata';
  $baseUrl = Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_WEB);
  $productMediaConfig = Mage::getModel('catalog/product_media_config');
  foreach ($ids as $id) {
    $productsArr = array();
    $products = $category->load($id)
        ->getProductCollection()
         ->addAttributeToSelect('*')
         ->addStoreFilter(Mage::app()->getStore()->getId());
    $i = 0;
    foreach ($products as $_product) {
        $baseImageUrl = $productMediaConfig->getMediaUrl($_product->getImage());
        $smallImageUrl = $productMediaConfig->getMediaUrl($_product->getSmallImage());
        $thumbnailUrl = $productMediaConfig->getMediaUrl($_product->getThumbnail());
        $heroImageUrl = $productMediaConfig->getMediaUrl($_product->getProductHero());
        $productUrlPath = $baseUrl.$_product->getData('url_key');
        $categoryName = $category->getName();
        $productsArr[$i] = array_merge($_product->getData(), array('category_ids' => $_product->getCategoryIds(),'price'=>Mage::helper('core')->currency($_product->getFinalPrice(), true, false),'size'=>$_product->getAttributeText('size'),'color'=>$_product->getAttributeText('color2'),'brand'=>$_product->getAttributeText('brand')));
        $productsArr[$i]['image'] = $baseImageUrl;
        $productsArr[$i]['small_image'] = $smallImageUrl;
        $productsArr[$i]['thumbnail'] = $thumbnailUrl;
        $productsArr[$i]['product_hero'] = $heroImageUrl;
        $productsArr[$i]['url_path'] = $productUrlPath;
        $productsArr[$i]['category_names'] = $categoryName;
        $i++;
        //echo '<pre>';print_r($productsArr);exit;
    }
    $jsonData = Mage::helper('core')->jsonEncode($productsArr);
    file_put_contents($jsonFilePath.'/c_' . $id . '_node.json', $jsonData);
  }
}

Also need lables of all attributes, like if I create any attribute, I can get it in my json file. how can I get this in my function?