Hi,

Using Desaturate (Ctr+Shft+U), and using saturation, both will make picture B/W but it looks very flat and dull.

Instead you can go for Black & White (Alt+Shft+Ctrl+B) and adjust each color to desired gray value manually is the best way to convert color to black/white image. this workstyle makes picture more appealing. 

I hope got the answer.

thank you,

-Ravi Kiran CG

layering is like seggregation of an element into multi components. This is not only stick to photoshop, also illustrator, after effects, premiere n many other good softwares are having this layering feature.

You are independent to reach to any creativity extent with this layer structure.

I hope u get the basic idea. For more, check  https://helpx.adobe.com/in/photoshop/using/layer-basics.html

in addition, https://photoshopcafe.com/tutorials/layers/intro.htm

Yes its amazing software application when it comes to mobile device.. but as far as windows, pc is concerned.. the Illustrator wins.. 

Though the both r used for vector art design.. illustrator is a leap ahead..  adobe is d champ with unlimited options with exceptional masters. 

Real world Sketching is the for a good illustrator. Get command over human figures, perspective, composition, staging & posing. Try various trends and styles to figure out your own style and comfort. Learn traditional/digital tools and techniques. Follow and study some great illustrators. All the best.

We cant decide which is better than the other, every software has its merits. some are free but have features like paid software..certain software cost us money but it provides us the pro level quality. if you are into professional use definitely go for photoshop. it is the most versetile pro grade software(PAID). If your a newbie trying to learn basic editing go for inpixio as it has a free version which offers basic and some intermediate function at free of cost.