5.1 LPCM on DVD is impossible........
24/96 5.1 in DTS is the highest possible , but..... the stream has the same specification as 24/48 ! IOW it's compressed more.
DVDA is really the only format that supports it.
In your toolbox I didn't see Surcode MLP..... and Discwelder Chrome.
For REAL DVD authoring I miss Maestro..... (still more than 80% of commercial DVD's are authored using a Spruce product !).
I say REAL here, because AFAIK it's the only one that makes fully compatible DVD's that will play on every machine !
About the 24 bits : always process in Plogue Bidule with the highest bitdepth : 32 bits or 32 bits float.
The last item before the filerecorder should be a dithering to 24 bits.
Although minimal, it gives better result to work this way than to do everything in 16 bits.
Especially when you're also upsampling before processing, it's a must to use a higher bitdepth. 16/96 for sure doesn't give you a good result
I really would like to hear your Tales version , because I'm an APP fan since that album came out..........