I hope that the little---I have been able to do does good to

I hope that the little___I have been able to do does good to them all.
请问
1 能不能把little看为形容词 填what ,让what引导I hope that 后的主语从句?
2 little , only , the one 等这些到底是算名词还是形容词 后面要用that来引导定从?
（我知道答案是that ,它引导定语从句）