To get to the stadium you have to click "..." then the cartoon speaking bubble (you know, like in comics when a character says something), this takes you to your advisors screen. On that screen, there's a link to "petitioners", go there. On that screen should be (so long as you've seen on the ticker that they are demanding a stadium) a petitioner about the stadium, go to that one and "select" it. On this screen you can accept or decline the stadium...THEN it appears in your "gifts" (but costs 75k).
Marinas - You have to build it on coastline that is perfectly straight. I don't believe (or haven't found a way) to build/take away costline to make it straight so it has to be on naturally occuring straight coast...built it a few tiles into the land, make sure it has a road, water, and electricity, and it should grow.
How do you take screenshots from an iPhone? Very cool...I want to!
Oh, water (when building pipes and pumps) and most utilities, etc. don't actually go into effect until the following month after which they're built. Hence the 3x speed ("> > >") makes it very nice you barely notice.