Crosshairs are the red lines that FF puts on your chart once the program decides you've ovulated. The vertical line is on the day of ovulation, and the horizontal line (called the "coverline") is just a visual tool to help you see the two different temperature phases.
If you want to play with it, put in a fake high temp for tomorrow. I'm pretty sure it will show you crosshairs if you do.
My understanding about BD timing is that, unless your partner has an issue with low sperm count, the more often you BD in the three days before and the day of ovulation, the better.
Looking forward to watching your chart over the next couple of days for that confirmed O!