Data Availability - Timing

At what point is the data just entered into a NEW form (as in data entry)
available to be used ?

I have a data entry form with the usual fields - ie Name; Address; Phone;
etc. I would like the new entries to be used to populate a combo box. So, If
I just enter the Name, can I use it to "lookup" other information based on
this Name field BEFORE I enter any mor ionfo on this data entry form ?

Just when is the data available ? Just when is the record written to the DB
? If I use Autonumber, I get the next autonumber immediately after i key the
first character into the form. Does this mean the data is written to the DB
at that time or is there some "delay' ?