Adding a new user to neo4j - graph

Question

A totally neo4j noob is talking here,
I like to create a graph to store a set of users, a typical user is as follows:
CREATE
(node_1 {FullName:"Peter Parker",FirstName:"peter",FamilyName:"parker"}),
(node_2 {Address:"Newyork",CountryCode:"US"}),
(node_3 {Location:"Hidden"}),
(node_4 {phoneNumber:11111}),
(node_5 {InternetEmailAddress:"peter#peterland.com")
now the problem is,
Every time I execute this I add 5 more nodes.
I know I need to use a unique key, but all example I saw can use a unique key for a specific node. So how can I make sure a user doesn't get added if it already exists(I can use email address as unique key).
how do I update the nodes if some changes occur. for example, after a week I want to update the graph to contain the following instead of the previous one.(no duplicates)
CREATE(node_1 {FullName:"Peter Parker",FirstName:"peter",FamilyName:"parker"}),(node_2 {Address:"Newyork",CountryCode:"US"}),(node_3 {Location:"public"}),(node_4 {phoneNumber:11111}),(node_5 {InternetEmailAddress:"peter#peterland.com"),(node_6 {status:"Jailed"})
(NOTE the new update changed location to "public" and added a new node for peter

Answer 1

Seeing as you had a load of nodes anyway.
Some of the data you have modelled as Nodes are probably properties as the other answer suggests, some are possibly correctly modelled as Nodes and one could probably form the or a part of the relationship.
Location public/hidden can be modelled in one of three ways, as a property on the Person, as a property between the Person and the Location or as the relationship type. To understand that first you need to have a relationship.
Your address at the moment is another Node, I think this is correct, but possibly you would want two nodes, related something like this:
(s:State)-[:IN_COUNTRY]-(c:Country)
YMMV and clearly that a US centric model, but you can extend it easilly enough.
Now you could create Peter with a LIVES_IN relationship:
CREATE (p:Person{fullName:"Peter Parker"}), (s:State{name:"New York"}), (c:Country{code:"US"}),
(p)-[:LIVES_IN]->(s), (s)-[:IN_COUNTRY]->(c)
For speed you are better off modelling two relationships which could be LIVES_IN_PUBLIC and LIVES_IN_HIDDEN which means to perform that update that you want above then you have to delete the one and create the other. However, if speed is not of the essence, it is common also to use properties on the relationship.
CREATE (p:Person{fullName:"Peter Parker"}), (s:State{name:"New York"}), (c:Country{code:"US"}),
(p)-[:LIVES_IN{public:false}]->(s), (s)-[:IN_COUNTRY]->(c)
So your complete Q&A:
CREATE (p:Person {fullName:"Peter Parker",firstName:"peter",familyName:"parker", phoneNumber:1111, internetEmailAddress:"peter#peterland.com"}),
(s:State {name:"New York"}), (c:Country {code:"US"}),
(p)-[:LIVES_IN{public:false}]->(s), (s)-[:IN_COUNTRY]-(c)
MATCH (p:Person {internetEmailAddress:"peter#peterland.com"})-[li:LIVES_IN]->()
SET li.public = true, p.status = "jailed"
When adding other People you probably do not want to recreate States and Countries, rather you want to match them, and possibly Merge them, but we'll stick to Create.
MATCH (s:State{name:"New York"})
CREATE (p:Person{name:"John Smith", internetEmailAddress:"john#google.com"})-[:LIVES_IN{public:false}]->(s)
John Smith now implicitly lives in the US too as you can follow the relationship through the State Node.
Treatise complete.

Answer 2

I think you're modeling your data incorrectly here - you're setting up each property of the person as a separate node, which is not a good idea. You don't have any linkages between those nodes, so with this data pattern, later on you won't be able to tell what Peter Parker's address is. You're also not using node labels, which I think could really help here.
The quick question to your answer about updating nodes is that you have to MATCH them, then use SET to modify a property. So if you had a person, you might do this:
MATCH (p:Person { FullName: "Peter Parker" })
SET p.Address = "123 Fake Street"
RETURN p;
But notice I'm making assumptions about the way your data is structured. I'll take that same data you provided, this might be a better way of creating it:
CREATE (node_1:Person {FullName:"Peter Parker",
FirstName:"peter",
FamilyName:"parker",
Address:"Newyork",CountryCode:"US",
Location:"Hidden",
phoneNumber:11111,
InternetEmailAddress:"peter#peterland.com"});
The difference with this suggestion is that I'm putting all the properties into a single node (instead of one property per node) and I'm applying the Person label to the node.
If you structured the data like this, then the update query I provided would work. Structuring the data like you have it, it's not possible to update Peter Parker's address, because there's no relationship between your node_1 and node_2