The web novels are often the original form, usually self - published online. Light novels, on the other hand, are more of a commercialized and refined version. Light novels may have better - quality illustrations, more polished language for a wider market. Web novels might be more raw in terms of content and writing style, with less editorial control.
Light novels are often more visible in the mainstream market. They are sold in stores, promoted more widely, and have a more polished presentation with their nice covers and illustrations. However, the web novels have a strong fan base within the online community. People who are really into the story from the very beginning and are used to reading online might prefer the web novels. So popularity depends on different groups of readers.
The first volume of 'Re:Zero − Starting Life in Another World' is quite popular as it sets the foundation for the whole story. It introduces the main character Subaru and the strange world he finds himself in.
Sure. 'Re:Zero − Starting Life in Another World' is a great one in the list. It has an interesting story about Subaru Natsuki who is suddenly transported to a fantasy world and has to face various challenges and mysteries.
It's hard to give an exact number because the publication of Re:Zero light novels is an ongoing process. You can check the official sources or dedicated fan sites for the most up-to-date count.