1)
We don't know with certainty that MHL isn't implemented via 3.5mm or mUSB, or cannot be w/future updates.
Thereby providing the N9 w/a means of 720p/HDMI output.

2)
DLNA's apparently implemented, but I've seen no evidence that a GUI for it will be included.
There's suggestions that future updates may include a GUI, but so far no official promises that I'm aware of.

What I want to know is... if DLNA will improve the probability of reliable 1080p output?
I'd assume it has very little bearing, & that the underlying WiFi transport (802.11a), how it's configured...
And overall signal quality to the client device, matters far more, but I'm not 100% certain...