(1) OK, since you are using attitude adjustment, you should not need to use the *old* ipks provided above (perhaps they don't work very well anymore). You can build this very PBX package by selecting it in "make menuconfig". It should appear alongside all the other LuCI apps. There have been many fixes and improvements since I released the original ipk and source for testing.
(2) To get func_cut, you have to select it from "make menuconfig" as well. It's under Network-Telephony, along with all the other asterisk-related stuff. The resulting package for me is asterisk18-func-cut_126.96.36.199-1_brcm47xx.ipk
(3) Finally, you should really simply make a direct calls between users for testing, not through google-talk, because any number of other things could be going wrong with google-talk. Lets say your users are 1111 and 2222. With the SIP client registered with user 1111, simply dial 2222 to ring the other user.
(4) I have not finalized the package dependencies of luci-pbx quite yet, but I agree it's time I did so. When you select luci-pbx, you should have all the necessary prerequisites selected automatically. It's on the TODO list!
(5) Here are a list of packages I have selected, which should help anybody building from trunk:
When you hit ENTER on the asterisk18 package, you get an additional list of chan and app packages. There I have the following selected:
I hope this helps! I agree that this should already be automatic, and I'm sorting all that out as I go along.