How to get last order status history comment and order status Magento 2

To retrieve latest order's comment history you can do following:

$histories = $order->getStatusHistories();
/** @var OrderStatusHistoryInterface $caseCreationComment */
$latestHistoryComment = array_pop($histories);
$comment = $latestHistoryComment->getComment();
$status = $latestHistoryComment->getStatus();

To add new history comment to the created order you can use Magento\Sales\Model\Order\Status\HistoryFactory and \Magento\Sales\Api\OrderStatusHistoryRepositoryInterface:

/** @var \Magento\Sales\Api\Data\OrderStatusHistoryInterface $history */
$history = $historyFactory->create();
$history->setParentId($order->getId())
    ->setComment($comment)
    ->setEntityName('order')
    ->setStatus($status);

$historyRepository->save($history);