What are the guidelines for drilling holes through rim or band joists

No. Since the band (rim) joist is continuously supported by the foundation wall, the boring and notching rules do not apply. You will, however, want to use common sense. Try not to notch or bore directly under a window or door, especially right where the king/jack studs are. You also don't want to notch or bore the entire width of the joist, in other words don't remove a section of the rim joist.

You'll notice the rim joist is a common place for dryer vents, furnace vents, electrical service cables, and other utility openings. This is due to the lack of notching and boring guidelines, which accommodates the placing of such openings.

I don't know what regulations allow, but I have never seen horizontal boring done without installing the HDPE flex conduit as part of the process.

They bore by pushing the bit forward until they hit the destination. Then they swap the boring bit for a pulling end, and pull the conduit back through the hole as they are removing the drill rod. There is no separate conduit installation from the boring; you can't realistically push conduit through the bored dirt afterward.

How are you planning on doing the boring? Is this something you are going to jerry-rig yourself, or hire a company to do? If you are hiring it out, they likely will have some leftover end spool. As you say, 30 feet is a small fraction of the 2000ft spool. It should not be hard to get that as leftovers from the boring company, I would think.

And if you are doing it yourself, perhaps you can still buy some end spool offcuts from a boring company.