What you could do is log into iTunes on the PC and get the apps you want there. Then go back to the App Store on your phone, go into updates and select purchased. You'll then see the apps you downloaded. If a previous version of the app compatible with your iOS available you'll be able to download that.
The apps that you're trying to install is more advanced than the iOS version currently running on your 1st generation iPad. If you're unable to update to an iOS version newer than what you have then you're going to be unable to install the app(s).