(Not sure about how the mods feel about self promotion but I can post a links later if they're ok with it)
I work at the store that sold Kill Bill their "show" katanas. Basically anything they didn't actually swing (those were Aluminum blades, some done by our friends at Renegade Effects) came from our store plus whatever they happened to have in their prop house. We sold them Paul Chen Practical Katanas and Practical Plus Katanas and they made some modifications to the Tsuba, wrap, and other things, on some of them. If you want a training blade you should pick up one of those so you don't nick the etching or hurt the finish of the sword.
We usually don't recommend Choji oil because it seems to yellow some blades. Some people like this because some old blades will have that sort of patina. I'm not really sure why some blades yellow (could just be a very light, minor case of oxidation) but it does seem to happen.
As previously mentioned, Renaissance Wax is excellent. It's better than oil in many ways because it doesn't attract dust or sawdust from the saya. The only issue is that it takes longer to apply than oil, so if you do a lot of test cutting or training, you may want to use oil during periods of consistent use and if you take a month off from using it you can throw the wax back on. If it's just a show piece, don't sweat it, use the Renaissance Wax.
In terms of other types of oil we do like and recommend, just about any acid free petroleum based oil will be just fine. Most branded "sword oil" is nothing but decent quality sewing machine oil. Hanwei Sword oil is the one usually sold with Paul Chen Katanas and happens to be the one we carry. I'm sure just about every other maker has their "specific" oil to pair with it.