Hi,
yes you can still create and use the old transaction types after the upgrade.
You will have to check your authorizations including imports, there have been changes in 7.1 which also effect the old transaction types. But you should be able to check this in your development system.
I do not think SAP supports newly created tickets in old transaction types in 7.1.
But i know of several customers who have done this without greater problems.
Hope this helps,
Christoph