Because DirectAdmin is designed to work on multiple distributions, which don't all use the same kernel firewall methods, it doesn't have it's own firewall. So that's correct, there's no firewall configuration utility in DirectAdmin.
KISS vs APF is a religious issue; some of us like one, and some like the other. KISS does NOT include any kind of brute force detection but there are other scripts out there that will work with a KISS firewall.
All KISS does is manipulate iptables.
Jeff