While I'm rambling here...
...might as well hit all the other comments, too...
MojoSetup does both of these things. The no-GUI mode option you mention looks something like this in the new UT3 server patch:
I think for binary only packages like game it makes sense to have a two path approach:
./UT3-linux-server-02202008.bin --ui=stdio -noreadmes --i-agree-to-all-licenses
It's a little chatty, but it gets the job done.
In the worst case, they're just self-extracting zip files at the end of the day:
cp -R data/* /where/i/installed/ut3-dedicated/
I would hope so, it's based on someone else's GPL code.
Will the new installer source code be released?
MojoSetup comes with its own uninstaller now, and will write out loki_setup-compatible XML files, so you can use it with loki_update, etc.
LGP has an installed title base out there. We'd have to come up with a converter for the uninstall/patch system already in place with the Loki derived LGP installer/patcher system. Not that we couldn't have done this, but I suspect Michael Simms is thinking in terms of the medium term answers here.
Granted, all of this work is recent, so it's not like LGP could sit around and hope it got done when they had titles to ship. I pointed out MojoSetup to Michael when I first announced it, and he mentioned he already had someone working on updates to his existing loki_setup fork...and frankly, MojoSetup wasn't ready for prime time when that conversation happened, so moving forward with updates to lgp_setup was definitely the rational course of action (although I'm not sure forking from loki_setup was all that wise, if that's what's happened here).
I really would like to see the actual changes, since the article here listed things that have been in loki_setup for some time (GTK+2 port and hackish xdg-menu support shipped with Google Earth, large file/install support shipped with UT2003, etc). If nothing else, I'd like to get things merged back into loki_setup where reasonable.