In regards to thongLoreto's first link,
You actually have two ways for the other fields bring up their data. You can use the method described in the link to copy the data into matching fields of your new record--that preserves a "snapshot" of what data was current at the time you created the record, or you can just place the fields from the related table directly on your "lookup" layout without copying any data at all.
The difference between the options is that with the second method, any updates to the data lookup table will automatically appear in all records that link to that company where the copied data will remain unchanged unless you perform one action or another that forces the record to re-lookup the data. Which approach is best for you depends on how you need to use this data.