Regarding the NCBI FTP site
Getting SNP data from FTP Site of NCBI SNP:

It's actually simple to download the data from the NCBI, if you follow the method given by FAQ( as given by @WYSIWYG).

Step 1:

Goto organism FTP: ftp://ftp.ncbi.nlm.nih.gov/snp/organisms/



Step 2

Open your required organism folder:





From here you can download any file you wanted. If you trying to study the whole organism please download any one of the whole folders(ASN.1, rs_fasta, XML(recommended)).

Now,

It's not about the downloading it's about understanding the files which are provided. 

files types:


XML files
ASN.1 or Abstract Syntax Notation One
rs_fasta


All of them contents almost the same data, just in different format. It's up to you how your script(preferably Python or Perl) works to get out the import information. 



Other way of Download from NCBI FTP:

You can always use filezilla:




Put Host as : ftp://ftp.ncbi.nlm.nih.gov/snp/organisms/ 
rest Username and Password, etc empty