Hi Conn experts,
thank you for this amazing software and for listening to the growing community needs and questions. 
I have a beginner's doubt regarding interactions effects between two continuous variables.

This is my study design (simplified with just 8 subjects):

All_subjects [1 1 1 1 1 1 1 1]
Age_covariate [45 50 54 49 47 42 43 52]
Scale_A [29 15 18 30 27 16 21 27]
Scale_B [8 9 12 6 6 5 7 3]

Scale_A and Scale_B are the scores in two different behavioural scales

1) I would like to see the effects of interaction of Scale_A and Scale_B on functional connectivity, and use age as a covariate of no interest. How should I set my contrast? [0 0 1 0; 0 0 0 1]? or maybe [0 0 1 -1; 0 0 -1 1]? or just [0 0 1 -1] and [0 0 -1 1] separately?

2) If the interaction is significant, then would it be ok to explore the relationship between the two variables by splitting the subjects in two groups (e.g. Scale_A high score; Scale_A low score) and then comparing the effect of Scale_B between them?

Many thanks for your kind help and support,
Davide