I like what you did with the sig. The render size is fine IMO but because of its size the canvas should be smaller. I'd make it maybe 400 or less in width and make the text smaller. One thing that doesn't seem to flow well is the uneven feel of the coloring. To the left of Davis is a bit desaturated while the right is a Ranger blue...just doesn't seem to transition well, could just be my preference though. All in all nice job, keep it up.
one thing to focus on while actually making the sig (assuming you're planning on using here at the cafe) is to cut down on the layers and colors as much as possible. try to only use what you need.
Something I never do and never will. The quality is going to take a hit. Deal with it. I'm not going to handcuff my creativity because of the inevitability of the cafe hurting a sig's quality.