Are the parts in bold your theories or were there actual lines from the novel to support those assertions?Qz martial arts and 9in martial arts were intertwined. so there are alots of similarites, that was the reason ZBT managed to learn 9yin zhenjing in his sleep after only memorising the formulas without any intention to practise it.
vacant fist and taiji had soft and empty, not using force similarites.
9yang emphasied balance in it's theories, while because huangshang had the aim of defeating his opponents, 9yinzhenjing became more yin(counterattacking) then 9yang. but as for inner power, the sanskrit portion of 9yin was as balanced as 9yang. it was the inner power part that had to be learnt for the moves that was yin. 9yang started from yang but balanced with yin as you practise. ZSF had pure and balanced inner power from the start. ZWJ inner power leaned towards more yang because he had to expel the icy cold yin xuan ming toxin from his body. it should become more pure with practise. 9yin started from yin, including the sanskrit portion but the sanskrit portion should balance with yang as you practise, same as 9yang.