No, it's not.
I only check the forums at MOST once a day. I'm working on the Hornet, trying to get the AGM-88 installed and fully functional. It's not an easy task for an XML newb like me, but I'm working through it. Takes a lot of my sim time, that I used to use for flying. I am enjoying the heck out of it though.
Point is, I may not check the forum every day, and I may or may not have an answer to your question. The true pro's at this are still active duty military, and may not be able to check the forums every day either.
So no, the forums aren't dead, but remember, patience is a virtue

To answer your questions, yes, you CAN in fact fly the plane using the KB, but doing so is NOT recommended. You can't get the fine control inputs you truly need to fly the plane correctly and well. IMO, a joystick and rudder pedals are the way to go, although given the qualities of the FCS, you can do it very effectively without the rudder pedals. They make doing the pirouette maneuver, and some others, much easier, though.
As to your second question: it sounds like you're using the autopilot during take-off and climbout. The autopilot in an F/A-18 is what's called a pilot relief system. It's really made to take some of the load of flying a high performance fighter aircraft off the pilot
for a short time. It allows him to set up systems for the next phase of flight, like landing on the carrier, for example, set up radios, program in new way points, troubleshoot problems that crop up, and so on. It is not made to fly the plane the way the big tube liners do. This is not flown by pushing buttons, like the big planes. If you're using the autopilot like the tubes do, it won't work very well.
Additionally, if you can't get the keyboard to work, are you using the command to make the mouse function as the stick? No, I don't recall it right off the top of my head. CTRL+K? I think? If you are using that, the KB will not function for use as a stick.
SO, you can try either making sure the AP systems are all off, and/or ensure you don't hit the mouse-yoke feature somehow.
Finally, are you using a saved flight that is NOT the sim's original default? The trike ove Friday Harbour. If you are, don't

Make sure that the sim is using the default default flight only. It sets up systems and various variables the plane needs to fly correctly. Once it's loaded all the way into the Free Flight page, then you can switch to the airport and plane you desire.
By the way, mixing the two versions won't function correctly. If you're using the v18.3 for everything, like panels, sounds etc, but the v18.4 executable, it won't work properly. Use one or the other. Don't play mix-n-match.
Does any of this help at all?
Pat☺