Speed and feed rate are very much a matter of personal comfort. If the pattern is very detailed, I would slow the saw down a bit to prevent overcutting in very delicate areas. If your saw has variable speed, you can simply turn it up, when you feel comfortable. I often change speeds during the cut and tend to run my saw at slower speeds than others. I know guys in my scroll saw club who only run theirs wide open. I rarely do. It's all a matter of what you are comfortable with.
1/4" plywood won't offer much resistance to a sharp blade, so I would go with the smallest blade I could. Again, this is dictated somewhat by the detail and complexity of the pattern, but the smallest blades will give you the most control. For a pattern with lots of detail, I would typically use a #2/0, reverse tooth blade. If using spirals, I would use a #2/0 or #3/0. If the pattern is fairly simple, I may go a size larger.
