Can't find 3 recipes which using chrome ingots
12 chrome ingots + 12 iron ingots + 12 nickel ingots = 360 molten iron
12 chrome ingots + 12 cobalt ingots + 12 titanium ingots = 360 molten titanium
12 chrome ingots + 12 steel ingots + 12 tungsten powder = 360 molten steel
So chrome smelting chain is useless at all???

It sounds like you are missing some mods from the pack. Install Sea Block Pack mod to get the full experience. If you do, you'll find that chrome is used for black circuits :-)

https://mods.factorio.com/mod/SeaBlockMetaPack

Thanks
Can i turn graphics of electronics from vanilla-style-veriosn to bob's electronics version?

I'm not sure sorry. Have a look at the settings from Artisanal Reskins. It's doing most of the reskinning work.