Hi kent,
Going directly to your question, I recommend you to make a mixed data cache of 20G with a page size pool of 15G and a large io pool of 5G and bound the database to it. Its not possible to separate indexes and data in different data caches because you only have two types of caches, logonly and mixed.
Then if you have 10G extra you can check sp_monitorconfig 'all' output or sp_sysmon out if you have to reconfigure something. If not, a 10G data cache for tempdb may be a good point but it depends in the tempdb size and activity on it because if its bigger and you have lot of activity you may degrade performance because of cache misses and more.
In order to know if you cache is full, check moncachedobject and moncachepool.
I hope this help.
Regards.
Javier.