17 is the LED/Switch panel for the Power button and reset switch it will not matter which way you plug them in. The Power led and hdd led must be plugged in a certain way for the LED to work properly (current in a diode only flows one way), I believe you want the side of the connector with writing pointing up (although if it doesn't work, flip it around, no big deal). The only difference I have seen here from this motherboard and any other that I have ever used is that for some reason they have a 2 pin Power LED and most Power LED connectors have an empty space between the + and - leads, so you may have to cut your connector at the empty space.
18. If your case has a speaker plug its connector there, again with writing side pointing up. Also this is another very standard connector for any motherboard.
21,22. Put your front USB ports on either of these, if you are lucky there will be a peg in your connector so you can only put it one way, otherwise look at the connector and there should be one wire missing, conveniently enough there is one pin missing on the motherboard USB header, match up the two missing connects and plug in. Look at Section 2.6 for a zoom in view of the USB headers.
26. This is a connector for a gamepad/joystick port. There was no such port bracket supplied with the motherboard, so I wouldn't worry about it. Besides, I haven't seen a non-usb gamepad in years.
27. Plug case connector in here if you have headphone/mic connectors on the front of your case, otherwise leave it clear. Again you want to match up the missing wire with the missing pin to get the correct orientation.