Hi Richard, I don't know about Palau copyright law but if there is one and if it's anything like most other countries then you have copyright of your material without doing anything. It's automatic. Having said that it is possible to register copyright in some countries (USA, UK etc.) which may give you some extra protection.
I have a DVD, "Reef Life of the Andaman" that is on sale in dive shops in Phuket. I don't have a written contract with any of them and have not really seen a need to have one and contracts can intimidate vendors. We keep it simple. We suggest a retail price but they are free to lower or raise it if they wish. Those who buy up front get a slightly better trade price than those who carry it "on consignment" (pay after they sell). The shops get a visit now and then for invoicing and re-stocking. Many shops are much more willing to take it on a consignment basis where they have nothing to lose other than a little display space, rather than commit up-front and risk having stock they can't sell.
If they have a TV set or spare computer then burn them a nice looper which autoplays and goes around and around all day so they don't have to restart it themselves every hour.
If you have confidence in selling a good number then go and get them properly replicated. We still burn/test/print/pack our own but it's time-consuming and there are still occasional coasters so we wish we'd gone for mass replication. If you go for mass replication then you can add some copy protection (Macrovision etc.), usually at an extra cost. The DVD can still be ripped but it takes a bit more effort. Part of the reason we didn't go for mass replication was that we couldn't find a trustworthy, reliable replicator here in Thailand and were concerned about excessive customs charges if we imported them. If you print your own then the Canon printers that do discs (iP4500, iP5200 etc.) are way more reliable than the Epson ones. Use good discs such as Verbatim DVD+R or Taiyo Yuden DVD-R.
When we were approaching retailers we made a bunch of promo samples, clearly printed as such, and occasionally during the promo there is crawling text: "This is a sample copy, not for resale or display. Order or license from Bubble Vision, Phuket, Thailand. email: XXXXX tel: XXXXX Thank you".
We also let a version out onto liveaboard dive boats around here and that one has this crawling text: To purchase a copy of this DVD, please see your dive center, call XXXXX or visit www.bubblevision.com".
We also got some display stands made out of clear acrylic. They carry 2 side by side with a space above for graphics.
As our source footage was PAL we sell 2 versions of the DVD (PAL & NTSC) and label them differently. That complicates things substantially but I wanted Europeans/Aussies/Thais/Russians/Chinese etc to be able to see the original PAL quality. If your source footage NTSC then just stick with NTSC which will play anywhere.
Oh, one more thing, make the "first play" item on the DVD a disclaimer that cannot be bypassed by the DVD remote buttons. But don't make it too long. Just a few seconds. Our wording is "The recording, copying, ripping, loan, unauthorised hire, public showing or broadcasting of this DVD is prohibited. Showing to promote scuba diving requires a licence from Bubble Vision" . However I am seriously thinking of the following wording for my next production, as suggested by John Cline on the Sony Vegas forum:
"I worked very hard on this disc. PLEASE don't copy it! Besides, doing so would be bad karma".
Good luck!