yakker, SkyAngel shows all frequencies it knows about for an airfield that's the destination in your planned route. Woodvale being military, the only frequency listed in the AIP is APP and we therefore don't have TWR data at the moment. I don't think the military AIP is published online unfortunately. [Edit: I've just found it. Shame on me.]
The problem of ellipsoid elevation versus mean sea level elevation is an interesting one. A few devices are "naughty" and report ellipsoid altitude rather than mean sea level altitude, and Navigo devices seem to be among these. This is obviously a problem when pilots are using car satnav units, whose manufacturers do not care about altitude, for aerial navigation. My advice would be not to purchase a unit that doesn't do the required conversion to amsl. I guess some products like the ones you mentioned are doing their own correction, but unfortunately I don't have the resources to build geoid correction into SkyAngel right now, so the best I can do is to detect the condition (this is easy) and allow manual calibrarion by entering the known altitude. This will work fine for trips that are not too long. In fact I can detect the fact that you're at an airport, and pre-populate the calibrarion box with the known elevation of the airfield. If you'd like to test this functionality in a preview build, contact me.
ETE should read ETA, I'll get that corrected. It is actually showing the zulu time of arrival. I do plan to have a "return to follow" feature for the mapping. I like your other ideas, too, but unfortunately at this stage I've got to stop adding new features to it and just get it polished so that it can actually be released this year. After release I'll then be able to start planning for the next version.