Using audio formats not AAC or MP3

[OgreVorbis]

So I'm trying to figure out what to do for audio after rendering my final video in VirtualDub2.
I hate the sound of MP3 and AAC (I'm more of an audio person). I'd like to use either Opus, Vorbis, or FLAC. I'm going to use H265 (but could do 264 I guess). Are any of those audio formats supported with H265 .MP4 file? Maybe using .MKV is acceptable?

Also, how do I get VirtualDub to not use stereo audio? It's capturing 48kHz with stereo, but my audio is all mono and I don't want to waste space for no reason. I know it's not a big deal to some, but it bothers me.

[traal]

AAC or AC3 at 320kbps should be indistinguishable from lossless.

I use .mkv because MKVToolNix makes it easy to combine streams, set aspect ratios and add chapter stops.

I don't know how to get VirtualDub to record mono, but I'd keep it on stereo anyway so I never forget to change it back.

I realize this doesn't really answer your questions as stated, but I hope it at least gives you some ideas.