Rats should have a climb speed. A rat and a squirrel are basically the same creature (except the squirrel has fashion sense), and we've all seen a squirrel scamper up a tree. Rats are just as adept at scampering, and are certainly more adept than cats, which do have a climb speed. I think this omission must have just been an oversight by someone unfamiliar with rats.
Do you remember the thread about the keelboat and how it made no sense and the designers were probably confusing the riverboat definition with the small sailboat definition? Ugh. The "sailing ship" is a similar problem, as that stat block is apparently meant to cover a vast array of vessels, some of which have substantial differences (substantial = actually matter in game play). It would be like having a single weapon called "sword" and expecting it to cover everything from a dagger up through a zweihänder. This seems like something that a couple of hours on wikipedia could have solved, easily.
Light sources have variable drop-off rates regarding dim light, which isn't how light works. For example, a candle sheds bright light for 5 feet and dim light for an additional 5 feet, while a daylight spell spreads bright light for 60 feet and dim light for an additional 60 feet. But the spread of light follows a simple inverse-square law, so the area of dim light shouldn't "stretch" just because the bright light is brighter. Once the light has dimmed enough to be considered "dim," there should be a consistent span of dim light.