Flags are similar to Variables. You can't display their state and I don't remember even thinking about this, but this is a good idea. Where to print such information is another question 🙂 You can try this "Change Status to" thing that each block has.
Yes, in "For each Trade" you can put multiple Group numbers, separated with comma, like this "1,2,3". This also works for market names.
If you use the Comment attributes of trades, note that if you have SL or TP and the trade is closed by SL or TP, some information can be appended to the comment by the broker. For example [sl] or [tp].