4) Did Paul speak to natural mean using spiritual milk,
It's 'milk' in the context, not 'spiritual milk'.
No. The 'milk' was given to babes in Christ, not the natural man.
1 And I, brethren, could not speak unto you as unto spiritual, but as unto carnal, as unto babes in Christ.
2 I fed you with milk, not with meat; for ye were not yet able to bear it: nay, not even now are ye able;
3 for ye are yet carnal: for whereas there is among you jealousy and strife, are ye not carnal, and do ye not walk after the manner of men? 1 Cor 3