Hello again, Brittany. You should follow the usual care instructions for potted plants: water more often than you would a hydrangea planted on the ground since the soil will tend to dry out faster; water once, wait for some water to be absorbed and then water again; remember to fertilize often since the minerals tend to be leech out thru the holes at the bottom (due to the all the watering).
You can use a liquid fertilizer or chemical fertilizer in pellet form or you can use organic compost, composted manure or cottonseed meal. The last three are general purpose slow-release fertilizers. The chemical fertilizer can be general purpose if its NPK Ratio is someting like 10-10-10 and it is slow-release if it says it is slow release on the label. Feel free to add minor minerals by using liquid seaweed, liquid fish or coffee grounds. Remember to keep the soil moist and fertilize at half strength during the winter months. Every 2 years or so, check to see if the roots are circling the pots and if so, consider if you need to repot to a biggger size or if you want to leave it potted in that size of pot.
The blooms go thru a plethora of color changes that varies from one hydrangea variety to another. Your plants are just doing that. The blooms usually stay a certain way for several weeks (2; 4 weeks max) before they change. Pink blooms sometimes add a green tint but all eventually end a brown-ish color. People up in the northern states like to leave the blooms "on" for winter interest. They will eventually fall off if you do nothing. In the case of reblooming hydrangeas, you can deadhead the old blooms and this will trigger new blooms (give it 2-4 weeks or more).
Leaves that are browning from the edges inwards suggest that there is or was a dry period where the soil lacked moisture. Not much you can to undo that other than -from now on- try to maintain the soil as evenly moist as you can. As Fall approaches, the leaves will change colors (usually to yellow) and end brown when the plant is dormant. You can leave them on or deadhead them. Eventually, they will "disintegrate".
The best location for the pot is one where the pot gets morning sun until 11am or so. Placing the pot in an area that is not windy may help conserve moisture. You can also place it in full shade as long as there is bright indirect light reflected by other things like walls, etc. I have some hydrangeas planted on the north side of the house and they get shade all day thanks to the house but the shade is not dense shade. It is what is sometimes refered to as "bright shade".
The stems will develop flower buds starting in July. They will be invisible and are usually located at the end of the stems. The buds will remain invisible and in the Spring of 2016, they will open and look like broccoli heads. New stems could produce flowers but, it is hard to know for sure. Many things go into producing the flower buds so who knows.
Some pests like aphids or mites could be munching on the sepals or maybe the sepals dried out enough where this issue is now occuring. The sepals look and feel paper-y when they dry out so, while I would not worry much, I would peek at night... when insects are active. Many like to take a bite of flowers/leaves and fly away so do not be surprised if you detect nothing.