Why are particle with half integer spins anti-symmetric while integer spin particles are symmetric? Or in other words, how does spin relate to the symmetry of indentical particles?
This is the spin statistics theorem. Google will find many references (it's hard to overstate its importance) but I am not aware of any proofs that work for an I-level thread.
One thing you do want to be clear about (you may already know this, but it's not certain from your post): The symmetry and anti-symmetry we're referring to is a property of many-particle systems. If the wave function of the entire system changes sign when any two particles are exchanged, we say that is is anti-symmetric, while if the wave function is unchanged we say it is symmetric.
I'd say the proof in Weinberg's, Quantum theory of fields is the best one in the sense that it treats the general case of any spin. That's A level. In most other textbooks you find the treatment of the most simple cases of spin 0, 1/2, and 1 (relevant for the elementary particles in the Standard Model), which is I level. In Germany the introduction to QFT is in the advanced undergraduate course (leading towards an MSc degree).