Jon, thanks for the questions. Everything in room acoustics measurements can be done with WinMLS ;-)
To get an answer on how to get high frequency resolution I suggest that you have a look under the Musical Acoustics part of the forum, see http://www.nvo.com/winmls/musicalacoustics/message.nhtml?profile=musicalacoustics&UID=10004
I recommend using sine sweep over using MLS for this purpose. And if you are using the latest betaversion, then go to Measurement->Swept Sine Settings... and increase the sweep duration to11 or even 22 seconds. At the very bottom you set the length of the impulse response, this should normaly be set to less than 2 seconds, but you can change it to 4 seconds, which will give you an actual frequency resolution of 0.25 Hz
About your smoothing question, please see the attached document (you will find a link to it somewhere above this text). Please let us know if you had success with this.
