I am comparing glutamate concentrations across groups (2 groups). Age was significantly correlated with glutamate while IQ was not.  

If there is a significant difference in variance between groups. Is this meaningful and what can I conclude from this? Most of the information about unequal variance reports that it needs to be cleaned up. However, can I make any useful inferences about the fact that my groups have different variances of glutamate?  

Does it make any difference statistically if you use a Type II or Type III sum of squares. From reading it looks like a Type II is preferred if you don't have any significant interactions and Type III if you do. What if you have some significant interactions for other metabolites and no significant interactions for my main metabolite of glutamate(I am looking at other things besides glutamate). I assume it must be standardized and you should go with either or for the entire analysis. What's the best way forward in this regard?  

Thank you for any help you can provide. I have been agonizing about these problems and just want to represent the data in the most appropriate way.