For the focal black and white, use the "Magic Wand Tool (W)" (there are several ways, but this is my favorite). It looks like a fairy wand with a star at the top. You can press "W" to go straight to it. When you select it, your top toolbar will change to options for the MWT.
You will see an option for "Tolerance" the lower this is set, the MORE difference in color it will detect. For example, if you have several shades of pink together, it will be very discriminatory. If you set it higher, it will be less selective. You can get away with a higher number if you have red against white, or two very different colors next to each other.
Play around with the tolerance to see where you need it to be for each picture you're working on.
Now, on to how to do it.
When you have it selected, click on what you want to stay in color.
You can hold "Shift" and click multiple times to select more than one area. Make sure that everything you want in color is surrounded by "marching ants" (the little flashing cursor looking hyphens). Don't worry if it selects more than you wanted, this means your tolerance was too high. Just go to "Edit>>Step Backward" or "ALT+CTRL+Z". This will just take you back one click and you won't have to start over.
Once you have everything selected that you want in color, create a new layer from copy. You do this by clicking "Layer>>New>>From Copy".
Now on the left you will see "Background" and "Layer 1". Click on "Background". This means you will be working on the background layer and the copy layer will not be affected by what you're doing. Now you want to turn the background layer to black and white. You do this by clicking (from the top menus) "Image>>Adjustments>>Black&White", or you can type (ALT+CTRL+SHIFT+B). It will give you some options on color control of the black and white. You can use the sliders to adjust the shades of gray how you want them.
You will notice that the item you selected before does not turn black and white because it's layer is on top of the background you're working on. On the left the layers can be moved by clicking and dragging them. Drag the background above Layer 1. Now it's all B&W. Drag Layer 1 back on top and it's back in color.
I love layers.
Hope this helps!