The problem is the jAlbum widget bar at the bottom. The Turtle page doesn't know it's there, so it doesn't leave space for it. That bar is added by jAlbum upon viewing the album, not by the skin. If you click the minus sign at the far right end of the widget bar, the second line of your caption will be revealed.
Offhand, I don't think there's a way to get Turtle to leave space for the widget bar, but maybe I'm just not seeing it. There is a sneaky way to pull it off, however. You can tell Turtle to put an extra line break after each comment, which pushes things up enough to clear the widget bar. See screenshot, attached.
But personally, I'd dump the widgets. If you want to keep track of how many people visit your site, use Google Analytics, which is invisible to the visitors (they don't care how many other people have seen the site, do they?). You've got "about" and "contact" info independently of the widgets. The only thing you would lose is the ability for visitors to leave comments, but that often turns into a spam magnet anyway.
I think it will take more than one page break, I'll adding another one or two. But perhaps your suggestion makes more sense... how would I deactivate that widget?
The quickest way is to head for Album > Settings > Advanced > Metadata and uncheck Include jAlbum widget support.
And... image upload size preference for this skin?
This is a responsive skin, so the images adjust themselves to the size of the visitor's monitor. Bigger images will give visitors with large monitors a better show, but bigger images also have larger file sizes, which might slow things down on a poor Internet connection, or from a lousy web host. There are always tradeoffs.
The Turtle default is, indeed, 960x720. If you've got a decently fast web host, I'd be inclined to push it further, maybe to something like 1600x750 (I use that as the default in several of my skins).