Few Queries on Dynamics NAv 6.0

Hi,
Greetings!
I have few queries & request your help on this.
For Nav Classic version-I can directly run the fin.exe from the folder & use the Navison application without the need for me to installm NAV.However in higher verisons of NAV,i cannot run the fin.exe directly.I also couldnt find the fbk file to create a new sample database.Can someone please help me how do I install NAV 6.0 or higher on my laptop & from which fbk file I need to restore to create a new database.

Also,
I m technical consultant & have few functional queries
1)I want to add a field on Vendor card(lets say parent Vendor) & would also like to group the parent on my statistics.Since I will be adding this on the master table,is it required to add me to all releavent tables like Vendor Ledger Entry,PO etc).I can only think of vendor Ledger Entry table & think PO or PI wont be required.Can you let me know what other tables I need to carry the new field which I will be adding to Vendor master table?
2)Also do NAV 6.0 have a functioanlity to determine the credit rating of the customer.Can you please throw light on this.

Thanks