Can Cassandra be used to increase database write rate?
...be expected to decrease the write time by increasing the number of nodes to which I can write.


Yes.  While the article is dated, Netflix performed a scalability experiment back in 2011, as detailed here:

Benchmarking Cassandra Scalability on AWS - Over a million writes per second

Essentially, they found that Cassandra was indeed linearly scalable.  That is, the amount of ops/second that your cluster can sustain is directly proportionate to the number of nodes in your cluster.


  the database supports strategic analysis and report generation, and not real time information


This is the part that makes me pause.  Cassandra is typically not a good fit as an analytics back-end.  The reason for this, is that (due to its distributed nature) your table structures must be modeled according to your read queries.

Essentially, that means one table serves one query.  Additional queries requiring different columns in the WHERE clause, typically have to be served by different tables hosting duplicate data.  This can quickly become cumbersome in an OLAP environment.

So while Cassandra's masterless, distributed architecture can help scale your writes, your reads quickly lose flexibility.