>1. I have a DBC in VFP5 with about 15 tables. I cannot find how to set relations in the DBC as has been done in the sample Tastrade DBC( with the lines signifying the relationship). Neither Help nor the manual tell me how.

Firstly, there are two types of relations: permanent and temporary. Permanent relations are used for RI-triggers and can be set in Modify Database builder: select primary key index in one table (parent) and drag it onto foreign key index in another table. Temp relations can be set either in DataEnvironment or programmatically by SET RELATION command. It's question of design approach what relations, if any, are reasonable to use. IMO, permanent relations are useful and temp ones are unnecessary.