Advice needed. Dioscorea Elephantipes

Greeting all.

I was gifted this lovely dioscorea elphantipes (d~13 cm) and Im trying to make my mind about its potting medium and pot size.

The previous owner had it in 50% potting mix and 50% cactus soil mix. I was however thinking of shifting it to manly pumice/ lava mixture say 70 or 90 % and cactus soil for the rest?. Also got some richer inorganic mixture with some higher moist retention (pumice 50%, lava 25%, Zeoliet 10%, seramis 15%, some carbon pellets)

Fo visual appeal id go for bonsai pot of 23,5*8,5 cm (inner diameter), yet i have read they gro much better in larger pots, the. I got one more of these terracotta pots 26*22 cm (hosting a cacti in the pic).

Finally, on the wine i could spot some insect cocoon stage. I removed them manually, but im wondering if i can treat the caudex to neem oil for prevention? Or just observe perhaps…

and got a little one, but still not sure it is alive as it has been dormant for nearly a year now, starting to water it now and then.. so i can draw no lessons from growing it yet.