That reddish, brownish tinge is quite common and can be from a number of things: puppy coat, diet, sun bleaching, genetics. It can be seen in all colours that have black. There are shampoos to darken blacks and put a shine on them

The breed standard describes the
ideal dog and
all dogs have faults. Many dogs who are showing are a bit long in the back, and Maudie certainly doesn't look too long. Don't get hung up on the measurements, it's the
appearance that counts. (she's still young too, and not finished developing!)
I know Maudie is in season so you can't go to ringcraft. Try to practice stacking her in front of a mirror, there are ways you can make her appear square with stacking. Get some good books on handling to help you out.
Don't be discouraged! Remember, all the dogs in the ring have some sort of fault according to the standard, and they also have good points too. Handling is about minimizing the weak points and accentuating the good!