Question: The title of the question pretty much tells it all.

When using the java SDK provided by Crystal Reports to export a report as an Excel spread-sheet. Although the cells grow even now, only the first line is visible in the export XLS. 

In the Crystal Reports UI, this is achieved by setting the 'Grow' option from the Report Export options.

What parameter must be set so that the corresponding cell *visibly* grows to accomodate large/multi-line text?

Answer: 
(Entity Framework *is* an O/R Mapper.)

If you're serious about getting your hands dirty with ORM (but relatively new to that area), I highly recommend something like TekPub's videos on these topics. You'll be able to see these tools in use starting from scratch. It is a graceful introduction to some simple, but real-world issues like the ones you mention.
I've had a great time using Entity Framework 4.0 (+ the CTP). I think you'd have a much easier time dealing with an ORM like that. EF4 provides *everything* you need to interoperate with MSSQL from C#/.NET. You won't have to write a single line of SQL, and it has full support for LINQ (through ObjectQuery).