Welcome to the forum. Your post is a bit hard to read due to the text color you chose - just as an aside.
Your mention of mixed instruction caught my eye - the saying goes, "Ask ten horse people how to do something, you'll likely get eleven different answers" - unfortunately, you will find that will likely be true here as it has been in the books and other resources you have been using thus far as everyone has their own approach to how they do things (including in working with horses). The key is to decide for yourself which approach YOU want to use with YOUR horse(s) and go from there.
The runny dung at two weeks of age is likely the "normal" foal scours - do a quick bit of research on it and you'll find it is actually quite typical for foals at his age. The old school of thought was that it was caused by the mare's hormones of her foal heat, but that has been disproved as even orphan foals of this age will show the foal scours.
I would be working with the foal now to get him accustomed to having the halter/head collar put on and taken off. I would also be accustoming him to having his body touched, handled and manipulated (ie handing his legs and feet). The more you can make "normal" for him from day one the less you will have to struggle to get him to accept later on when you decide to start doing things with him.
What hard feed are you giving your mare? It may or may not be appropriate for a foal. If it is appropriate for a foal, allow him to continue doing what he is doing - and, yes, it is normal for him to be exploring and consuming that feed (which is why it is important to make sure that what is accessible to him is appropriate feed).