I'll answer your first question, the second one someone else gets to answer who's been here longer than me.
Yes, you can hide it with CSS, there's a good guide here:
Here's an example CSS for what you want to do, for tile number 11:
#tile-11 .dimmer,
#tile-11 .dimLevel {
display:none;
}
Though that might not look great, here is another:
#tile-11 .dimmer,
#tile-11 .dimLevel {
visibility: hidden;
}
