Development Using PC Oracle?

Could anybody provide me with information concerning the use of Oracle as a development tool on the PC (DOS/Windows) platform?

I am planning the development of an application that would need to be portable across database platforms, hardware platforms, and user interface environments (of course every database vendor can provide this if you use their tools :-) ). The coding will be done in C with functions to perform SQL calls to the database. C will give me the disered level of hardware independance I'm looking for. And I figure the database functions will be as straight forward as they can be using SQL.

The user interface concerns me.... I know with some forms packages that you can create the form and compile it into object code to be linked with your application for use without connecting to the database (ala Vifred from Ingres or Open Interface from Neuron Data). This implies that the code drives the form.  

I need to know the following:

1. The ease of developing applications on the PC for porting to other Oracle platforms (i.e., VMS, OS/2, UNIX, etc.). What technical issues exist (known problems, etc.)? What licenseing issues exist?
2. Does SQL*Forms need a database connection to work (can you "drive" the forms from the code without establishing a connection to the database)?
3. Any other details that would help me make an informed decision.