@DNS: You don't need any SRV records if the jabber-server is the same machine (or firewall) like machine/IP behind the A record. If your hostname differs from the jabber-hostname, you need the SRV records. Example: example.com is your webside, jabber.example.com is your jabber-server and your JID is jason@example.com => you need DNS records. if your JID is jason@jabber.example.com an A record should be sufficient. (I'm running both kind of servers with openfire)
@Ports: For S2S (Chat, Groupchat, Presence) you only need 5269 (or the port in your DNS record). For other services some other ports or ranges could be needed. BOSH, SIP, etc.
@S2S: Please check your SSL certificates of both servers. You should prefer ssl certificates of an official CA like startssl.com (free). But you could use self-signed certificates as well if the remote server allows them. Check your SSL-settings and look into the server session overview, click on the server name and check the directions. Errors due certificate and/or connection issues should be shown in error log.
Best hint: Check your server connectivity with xmpp.net - all issues recarding connectivity and ssl encryption could be checked there (free).