Firstly, check your network connection. Can you successfully load a webpage in Safari?
Try restarting your device, and see if they begin to download then. You may also like to sign out of your Apple account in Settings>iTunes and App Stores>Apple ID>Sign Out. Then sign back in again.
You can cancel downloads by holding down an icon and tapping the 'x' in the corner. You will not have to pay again if you redownload it.
Below is a relevent support document which may also be of help:
Have a great day,
Reboot the iPad by holding down on the sleep and home buttons at the same time for about 10-15 seconds until the Apple Logo appears - ignore the red slider - let go of the buttons.
Make sure that you do not have a stalled download in iTunes - a song or podcast .... if you have a download in there that did not finish, complete that one first. Only one thing can download at a time on the iPad so that could be what is causing the problem.
If that doesn't work - sign out of your account, restart the iPad and then sign in again.
Settings>iTunes & App Store>Apple ID. Tap your ID and sign out. Restart the iPad by holding down on the sleep button until the red slider appears and then slide to shut off. To power up hold the sleep button until the Apple logo appears and let go of the button.
Go back to Settings>iTunes & App Store>Sign in and then try to update again. Tap one waiting icon only if necessary to start the download stream.
You can also try deleting the waiting icons - tap and hold down on an icon until it wiggles - the tap the X on the icon to delete it. Then try to download again.
You can try resetting all settings. Settings>General>Reset>Reset All Settings. You will have to enter all of your app preferences and device settings again.
If all else fails, download the updates or the apps in iTunes on your computer and then sync the content to your iPad.
I'm having this same issue with my iPhone 4S. These apps were never on this phone, but were on my 3GS. I downloaded iOS 7 and these "new" apps showed up dark. I tried deleting them from the phone, but they won't delete because they aren't on the phone. I've tried shutting down, the reset holding the lock and home buttons to no avail. I don't want these apps and just want these icons gone from my screen