Database Software

I am not sure if I am posting my question in the right section. Pl advise if not and if it is the relevant type of question this location is supposed to address to.

Overview: I am working on a MIS DWH project (lone soul for the whole life cycle of the project - one man show). Data is coming from different regions on which reporting needs to be done using Oracle Discoverer. I shall be dumping all the data files into tables on a one to one basis.

Questions:

1. Should I be use the object 'Dimension' to create my dimension tables ie. use statements like 'Create Dimension...' and base my dimension on the source data tables, also putting in the heirarchy structure as per the syntax. What puzzles me is that an old MIS solution had no dimensions instead the dimensions used in Discoverer are actually table with names 'D_'.

2. How will the fact table be create if I go by 1 above using 'create dimension...'. I know that the Fact Table will have all the foreign keys of the dimensions (contributing to become the primary key of Fact table), but where does the DDL for the creation of Fact Table come from. Shall I have to write manually. (i am following star schema for the DWH)

3. I have 6 important dimensions and the fact table has amount to be reflected in these 6 dimensions. People want this amount to be reported (all reporting is thru Ora Discoverer) in other currencies and are insisting that I add another dimension for currency. For me it is not a good idea. How could cater for this without having the currency dimension given that users in Discoverer will just be working with the Fact table and the dimensions. How does the 'calculations' part in Oracle Discover convert the amounts in different currencies.

Thanks

Appreciate a quick response since I have a tight timetable and I am into design.