Can I access my husband's iTunes acct. from my iPad? i have his permission & pass code. We want to keep all music in one place & family accessible.
Yes you can, sign in his Apple ID and password in
Settings > iTunes > App Store > Apple ID > here to share purchases from App/iTunes/iBook Store.
If you log into his account and download some of his past purchases on your iPad then you risk tying your iPad to his account for 90 days : iTunes Store: Associating a device or computer to your Apple ID
But it looks like that might change when iOS 8 is released in the Autumn (no date has been announced yet) : http://www.apple.com/ios/ios8/family-sharing/
If you have his content in your computer's iTunes library then you could sync it from there instead of risking the 90 days association on your iPad. If you don't then you could copy it from his computer and then sync it to your iPad e.g. copy his music to a flash drive and then add it to your library via File > Add To Library