First tip:
VOR and ILS frequencies can be entered as you please, either as Tacan channels, or as a standard frequencies. The radio is smart enough to figure out your intentions, and can even use shortcuts.
For example: to set an ILS at 108.90, you can set it as a Tacan channel 26, by entering ILS mode, dialing 2-6-ENTER on the keypad, and keep the UFC window indicator to have the X showing the : symbol. That's you probably already figured it out.
To tune by frequency, just dial 1-0-8-9-0-ENTER, it will automatically translated into a Tacan channel if recognized.
To set course, just use the CRS switch close to the Fuel indicator. It can be scrolled with the mouse wheel. To check the actual CRS, check the HSI page on the MFD display: there's a small CRS readout that indicates the selected course.
Note: there's only one VHF radio on the F/A-18, so you either use it for a VOR or for ILS. There's no OBS2.
The Autopilot is a little bit more complex, I'll try to prepare a reply tomorrow (it's 3 AM now in Italy...), starting some discussion on the Autopilot.
