There is an amazing variety of these, not only types (30, 38, 44, 99, etc.), but even length within the general types. The most common are the Type 99s, which are chambered in 7.7x58mm, in the short rifle length of roughly 25", and the Type 38s, which are chambered in 6.5x50mm, in long rifle configuration. You need a picture of the receiver in the area of the mum to figure out the type. The left side receiver rail will have the manufacturer's and series marks, as well as the serial number. This is a good internet guide with some of the basic info and the Japanese numbers and characters:
Markings on Japanese Arisaka Rifles and Bayonets of World War IIThe holes are just over-pressure relief vents. Serial numbers (last 3 numbers of the receiver SN) are found in quite a few places on the rifles: barrel bands, bolt and often various bolt pieces (including firing pin, safety), etc. Items that affect value besides the mum and bore/stock condition are, the presence of the receiver cover, anti-aircraft rear sight "wings", monopod, and matching numbers (fairly unusual). Ammo for the Japanese rifles is expensive and a bit hard to locate on a regular basis. The prices can be quite low for the common T99 and T38 rifles. As far as the note tag, I'd try to get it if you buy the rifle but I wouldn't pay extra for it or the rifle on that basis alone. That and the bullet are certainly potentially unique features.
Blicero can correct or add.