There is a tool called AMT Commander that should allow you to perform the actions you mentioned. You can download it from here:
Let me go through the items you mentioned:
-Connect to a wireless only computer via an encrypted connection.
In order to connect to a machine wirelessly you must have a vPro enabled laptop with AMT wireless settings configured (you can configure wireless via the AMT web console). The laptop must be plugged into AC power for wireless functions when the PC is off. In order to encrypt your connection you must setup the approraite certificates and configure them (this may be difficult without certificate experience). If you choose a non-encrypted channel remote operations are still protected with username/password authentication.
AMT Commander supports power on as well as the integrated WebUI.
-Decrypt the harddrive which can only be decrypted in a pre-boot environment.
If you are using a software based encryption product you may be able to utilize serial over lan. AMT Commander should allow you to do this and enter your credentials via the AMT Commander terminal. This may or may not work depending on your encryption solution, generally it will work for text-based screens; best to try it out.
Intel Remote KVM may also work here.
-View and manage the desktop.
Intel Remote KVM should do the trick (AMT commander or RealVNC viewer). The laptop must have AMT 6.0 or later and must use Intel integrated graphics
AMT Commander supports power off as well as the integrated WebUI.
-Do this all without advanced knowledge of networking.
Gotta love the vpro expert center :-)