SAMBA, FTP or ???

Hi, I'm did some work for a NGO, setting up a small wireless network with SAMBA server. The office has 6 PCs, 4 WinXP and 2 Win98SE. Now I have two problems: 1) Win98SE connects to SAMBA but it takes ages to open folder or put the file on the server. The same thing in XP works instantly. Why is that? 2) They want to enable that users from other cities have access to the server. It's a DSL connection and, as I said, with Wireless Access Point. What is the best way to make that possible: with SAMBA (I know there is some security issues with SAMBA shares over internet), with FTP access or something else? What ports I have to let pass through DSL router in case of SAMBA? Any comments are appreciated, Thanks, Dejan