MySQL NDB Cluster architecture?
Yes, you can put different node types on the same machine.  But...  You need to change the configuration of each.  Running out of RAM would be really bad for performance.

For a Web application, I see no need for the complexity of NDB Cluster.  Virtually all Web usages of MySQL simply use InnoDB.

Before digging into more details, please state your goals.  Redundancy?  Resiliency?  Scale?  Key-value store?  Other?  I don't hear any of those in your Question.