hello
for 1)
make a table of 2 cols (in whichever database software you are using) and insert login names and phone numbers in pairs.
when retrieving them, fire a query (i dont know how in Access!!) like "select * from phone_table where login="login_name"
this will retrurn all phone numbers for a particular login
2)make another table with phone number as primary key and have columns as per the data you want to store,
now you can link both tables on basis of phone numbers(assuming that 2 people do not have same numbers). you can now know to which a phone number belongs. and once you have the number you can get all details
sample tables
phone_table
login phone
q 12345
q 667778
a 66666
phone_details
phone name city b'day (and so on)
12345 asdf llll 23-4-76
do you get it?
cheers!