Bravia - what does not transcode?

I have a Bravia KDL-40HX800 and I use the Bravia 2011 profile. I can stream MKV's, with H264 content, and it appears they are transcoded. This is okay, but I'd like to know:

1) What, if anything, can be played on the Bravia directly without transcoding? I'm wondering so I can maybe think about converting my DVD and Bluray ISOs to the best format for streaming to the Bravia.
2) If the MKV contains formats the Bravia can play directly, like the video for example, does Serviio still transcode the video?
3) Is there any way to play DVDs, and get chapter and subtitle support?
4) Is there any easy way to see if something is being transcoded? Right now, I look for ffmpeg in task manager, and also see if any files are in the temp folder.

[Illico]

1) What, if anything, can be played on the Bravia directly without transcoding? I'm wondering so I can maybe think about converting my DVD and Bluray ISOs to the best format for streaming to the Bravia.

A stream is composed of containter (mkv,avi,mp4,mpegts,mpegps,etc), video codec (avc/h264,mpeg4,mpeg2,divx,etc), audio codec (ac3,mp3,mp2,dts,etc) and optionally subtitles,etc.
For Sony bravia TV device, I think that the best format is container MPEG2TS, video codec AVC/h264, audio codec AC3, but subtitles are not supported.
For 2011 model, you can have a look at Dix with DivxSub, but need some test to confirm, and its limited to SD format.

2) If the MKV contains formats the Bravia can play directly, like the video for example, does Serviio still transcode the video?

When video and audio codec are supported, they are remux to mpegts container, not transcoded (less cpu load)

3) Is there any way to play DVDs, and get chapter and subtitle support?

Not yet.

4) Is there any easy way to see if something is being transcoded? Right now, I look for ffmpeg in task manager, and also see if any files are in the temp folder.

You can enable detailed loging and see in the file is delivered "in native format" or if there were a ffmpeg process.