1.When installing it on several supposedly identical VPSs ARM won't start on one because it can't find components where they should be. I got a limited, incomrehensible (to me) response from the author so it stays unresolved.
2.ARM asks for a password which doesn't exist which is connected to the opening of the control port in torrc i.e. removing the # at ControlPort 9051 and then choosing HashedControlPassword or CookieAuthentication 1.
It would seem that a graphic programme like ARM would be good to help people who want to run a relay but for whom the command line Linux will be insurmountable and deterrent.
Robert