The Snowflake processing is based on SQL

Correct. In order to change the type you will need to re-create the table with the desired table type

Please see the below link for detailed syntax on virtual warehouse creation

https://docs.snowflake.net/manuals/sql-reference/sql/create-warehouse.html

External table being outside of Snowflake, don't have the same optimizations as a native Snowflake table, therefore querying an external table is slower.

https://docs.snowflake.net/manuals/user-guide/tables-external-intro.html

All are examples of date / time data type. You can find more date/time data types at https://docs.snowflake.net/manuals/sql-reference/data-types-datetime.html

When copying data to a Snowflake table from cloud storage, the data is encrypted as soon as it is loaded into the Snowflake table.

https://docs.snowflake.net/manuals/user-guide/security-encryption.html#end-to-end-encryption

Data in Snowflake tables is encrypted automatically using AES 256 strong encryption

When copying data to an internal stage the files are encrypted on the client machine before they are transferred to the internal stage.

https://docs.snowflake.net/manuals/user-guide/security-encryption.html#end-to-end-encryption

A running virtual warehouse is required for unloading data from Snowflake. A running virtual warehouse will be needed even in cases when you are unloading using a query, where the query results are cached. This is because a running virtual warehouse is needed to be able to write the rows to the output file(s).

https://docs.snowflake.net/manuals/user-guide/data-unload-snowflake.html

External tables can be partitioned. This is dependent on if your data is residing in a logical folder structure which allows effective partitioning. If you have Enterprise license (&above) you can create materialized views on top of the external table Incorrect: Columns in external table can not be compressed or stored as columnar format https://docs.snowflake.net/manuals/user-guide/tables-external-intro.html#partitioned-external-tables

https://docs.snowflake.net/manuals/user-guide/tables-external-intro.html#materialized-views-over-external-tables