Port 53 just means DNS, and yes, ns1.dreamhost.com (and ns2 and ns3) are DNS servers. Dreamhost's web servers are not going to be listening on port 53, but Dreamhost's name servers definitely are (it's their job).
I'm curious what whois says. For instance, if I type "whois sarastro.org" at my shell, then I get a bunch of stuff that's too long to copy and paste, but part of it is:
The text is formatted differently from registrar to registrar, but it always has the same basic stuff in it.
First your nameservers have to make it into whois (which is more or less bookkeeping data, and doesn't affect DNS resolution). Then they have to make it into the root DNS servers for your TLD... it looks like .il is being served by:
il. 172800 IN NS sns-pb.isc.org.
il. 172800 IN NS ns-il.ripe.net.
il. 172800 IN NS nse.ns.il.
il. 172800 IN NS dns8.denic.de.
il. 172800 IN NS ildns.huji.ac.il.
il. 172800 IN NS nsd.ns.il.
il. 172800 IN NS nsb.ns.il.
il. 172800 IN NS lookup.iucc.ac.il.
Then finally, those servers are going to be handing out responses with a certain TTL, and so you have to wait for that length of time (whatever the TTL is) to be sure that people on the internet who had a cached copy of your NS records no longer have the old ones.
The bad news is, the .il nameservers seem to be handing out a TTL of 86400 seconds (1 day). That TTL is unlikely to be different between different registrars, so I just picked a .co.il domain at random to try this on:
dig +norec @nsd.ns.il -t NS petri.co.il
;; AUTHORITY SECTION:
petri.co.il. 86400 IN NS ns2.easydns.com.
petri.co.il. 86400 IN NS ns1.easydns.com.
So "it may take a while". But do check whois... if Dreamhost's nameservers are listed in whois, then you're well on your way and the rest is probably just waiting.
To my knowledge, there's nothing special about "foreign" domains... or if there used to be, then that's all gone in this age where European folks all have .com domains and americans are snapping up .tv and .fm like there was a reward.