Both the Hoya R72 and the Cokin work well in my (limited) experience. It is worth studying the longish document that Efke posts about this film on their web site. If you want the IR "bloom" be sure to get the version of the film that has no anti-halation coating.

If you accept the manufacturer's rating of ISO 100 for the film, and add five stops for the infrared filter, you wind up with ISO 3. But 1.5 is probably better in most situations. In any case, bracket generously, since it is very difficult to assess how much infrared is actually there in any given scene.

Don't know where you plan to be shooting at this time of year, but generally there is more infrared in early morning or late afternoon, in spring or early summer. Another advantage of spring shooting is the little tiny leaves that are just busting out. Although these look green to the eye, they actually reflect tons of infrared, making for shots that look almost like snow scenes.

It's kind of unpredictable stuff, so just decide you're going to have fun experimenting!