PROBLEM A: Double
At first glance, it looks like partner with H support and weakish hand is messing up the opps. But wait a minute, why partner didn't bid 5H then, it preempted both 4S and 5C by opps. With white vs. red, that would be the best option. So my conclusion is partner who bid 4NT, didn't have H support, but a good hand with likely H small singleton. I hope my X tells partner I have one defensive trick and hope partner can make a smart choice.
PROBLEM B: 3 Diamonds
My motive of the 3D bid is partner probably has club shortness. I can imagine a Diamond game vs. 13 count partner.
PROBLEM C: 3 Hearts
Right points and shape for 3H bid.
PROBLEM D: 2 Spades
I don't like to double with a void and I don't like to see a 3S bid by West after I bid 2H. So Michaels, introduce my two suits now.
PROBLEM E: 4 Diamonds
The hand has 8 tricks itself, but where's the 9th trick for 3NT if you can't get to partner's hand. If partner doesn't have the HA nor the SK, there's almost no way to make 3NT, but there are still chances to make 5 level minor game (like a singleton Heart). If partner has either of those, both games would probably make. So I'm on the path to 5 level minor game. 4D here is key card asking for clubs. If I hear the best news, I'd go for 6C, otherwise, I will settle in 5C.
One thing conerned me is the Match Point scoring. Pass could be a good strategy for it.
PROBLEM F: 1 Spade
Just a 3rd seat opening, also a leading directing.
PROBLEM G: 2 Hearts
I don't like my H suit, but I don't see other better choice.
PROBLEM H: Heart Ace
Take a look at dummy first.