When I use the tag attribute in an Order, the respective 'day' set of positions should also have the 'tag' attribute present while querying positions. But I do not see the 'tag' attribute documented h
You don't need to poll orderbook. You can listen to order updates on Websocket API and use that as an event to fetch orderbook and check the latest status of the order.
You can refer more about WebSocket order status: https://kite.trade/docs/connect/v3/websocket/#postbacks-and-non-binary-updates & https://github.com/zerodha/pykiteconnect/blob/a6be72a05edcb22f44
Basket orders are not available on Kite Connect. You need to create a queue or list at your end and place order in loop. You can know more about order placement APIs here.