Yupp, an estimated waiting time counter is lacking in the game. Many suggestion were made and are being made again and again
However, if your gear and skill is good for normal, but not yet sufficient for hard, you should choose normal. You shouldn't see "oh, on hard I get quicker games", then choose hard, then hinder your team and annoy everybody.
Same reason as above. I think you yourself wouldn't want that a way lower eff. guy is in your game, just hindering and annoying you.
The whole problem (both points) is finding its source in the too the small playerbase.
Playing with friends, yeah, another problem, but I kinda understand it. I mean in what universe is it fun when a 30 full gear full runes full amulets guy plays against or with a Lvl 1?