Nice pic of Shiva.
Well, they way her almost mastered use of her Zanpakuto's Shikai form is id say you would be right. I believe she would merge and be part of the physical form of her Bankai.
- She has not yet achieved Bankai. The furthest we've seen is her sword in shikai (White as snow) and using her ice pillar attacks.
- Negative 10,000 degrees, im sure he was exaggerating that factor. Besides Rukia has to finish mastering freezing her body temps to exceed the 4 second limit at absolute 0 degrees (-273 Celsius), which otherwise can kill her (irreparable damage to cell regeneration).