full是形容词,full of “充满...”之意.
Who do you have much to say to?这是个特殊疑问句,你可以先把它还原成一个陈述句：I have much to say to John.然后对John划线部分提问,就成了上面那个句子了.
分析句子成分,你可以根据陈述句来进行.
I 主语
have 谓语
much宾语
to say to John是宾语的定语,意为“要对John说的”
在疑问句中,do是助动词,无意义,帮助构成疑问句而已.
who是介词to的宾语.