Plotting surfaces in 4D

So I am new to Mathematica and I will probably express myself badly, please let me know if I should specify the problem better.

I have the following constraints over the list {a,b,c,d}:

a=f[c,d] b=g[c,d] 

So that effectively I have {f[c,d],g[c,d],c,d} and I would like to plot this in a 3D+Color graph, with possibly one of the functions as color. I tried various combinations of Table and ListDensityPlot3D but I wasn’t able to reach anything (apart from a sparsely colored cube).

Moreover, I have a second surface {f2[c,d], g2[c,d],c,d}, is it possible to plot the two together and possibly find intersection points?

Thanks for the help.