IMO piats are quite strong. It's really a decent extra AT capability! Just make sure you have some regular AT guns(BritATGs seems quite strong to me as well). Then you should have no trouble. Just 1 ATG that is well placed should get you really far in the lategame if you have 1-2 PIATS to support.
This is usually what I end up with (almost every game lel...)
Yes, they can fire at stuff that moves. Regarding the bren-gun. I usually dont end up putting it on that many squads cause I use munitions very ability/mine based. But the brengun assures that you win a LOOOOOT of ingagements with your basic infantry. They are really good to boost your infantry with. #AxizRekt
They are my best ranked army, but I have only played 15 games, so Im still at a learning curve. But I hope this helps anyway!
