How Do Spin, Isospin, and Charges Interact in Particle Physics?

[kith]

Recently, I was thinking about spin and isospin. It's been a while since I've dealt with particle physics, so my knowledge may be a bit rusty.

In the Standard Model, we have three interactions with associated coupling constants e, g_w and g_s. A particle may have three different charges Q_e, Q_w, Q_s which are multiples of e, g_w and g_s. Also we have three types of spin -"ordinary" spin, weak isospin, strong isospin- and their projections S₃, T₃ and I₃.

These spin projections are related to the interactions but it isn't a one-to-one correspondence. Neutrinos for example have Q_e=0 but S₃ = ±1/2 and the weak isospin depends on Q_e. Does this mixing of interactions only reflect the fact that we need the unified electroweak theory to explain some experimental facts or is there more to it?

Also, are the spin projections together equivalent to the charges? If yes, what is the idea of these different concepts and when do we use which one? If no, what's the difference between them?

Thanks
kith