Scripts to disable constraints and indexes for data warehouse load
For a few things that you may have not considered:


If an index starts as disabled you'll end up rebuilding it after your script finishes.
If an index starts with page compression you'll rebuild it without compression.


For performance:


Since no other process is accessing the table you could rebuild with the ONLINE = OFF option for possibly a small performance boost due to less locking.
Depending on the size of tempdb and your indexes you could use the SORT_IN_TEMPDB = ON option for a performance boost.
You're updating statistics on all tables, even if that table hasn't been modified or had very few rows changed. You could try to be more restrictive in your updates and only look at tables that were modified since the last stats updated or were modified at all.
It looks like you're running all of these queries in a single session. Have you considered splitting up the work among multiple sessions?