Win98 - Linux connection (with ADSL) doesn't work. /CORRECTED

[Marcello Pietrobon]

I'm not able to connect my Win98 PC to Linux!

I'have an ADSL connection to a provider, and it works.
I've installed a Linux Server (Apache is working).

I need to make Win98 able to see the Linux files and also able to
connect to internet protected by the Linux-server firewall.

This is the configuration, (where E# are the ethernet cards).

  Windows 98
      |E2
      |
      |E1
linux server with firewall
      |E0
      |
ADSL modem
      |
      |
   internet
 
The following is the main question.
 1) Should I choose  Share-level or User-level access in Network
Neighborhood ?
	Which one is the safest ?
    Should I choose security=user or security=share in smb.conf?
    If I choose User-level access, should I choose 'Windows NT domain'
as
    'kind of autenticator'?

Also would be useful to understand:
 2) Win98 doens't know the server name.
	Sympthom:
    Computers can ping each other using the related IP addresses.
    Linux can use also the host name.

 3)   How do I configure the Win98 DNS entry ? 
       Should I use a private name or the provider name as domain ?

Thank you very much for the person wich will give me some light!

Ciao

           Giovanni