Yea i use alot of different layermodes, i usualy start with overlay or a softlight layer to give my grayscale the basic colorwash. Then i merge it and start painting on top and through the process i adjust colors here and there with more softlight or other layermodes. I hope it helps!
No Problem, just try to watch your Values when working with layermodes, they usualy mess the values up alot. You can check it every now and then if you put a new layer on top of your otherlayer, fill it with grey and put the layermode on color. Then just switch it on and off to check your values every now an then. Cheers