Other Short question about iPhones, apps and website data

[peachesforfree]

My SO downloaded Snapchat on their phone behind my back and we ended up having a conversation about that and all was resolved with the app being deleted. The same thing happened with Viber. You might know these apps - they're the ones that you can "never remember downloading". However, it has left me with some questions. 1. In the Safari > Advanced > Website Data, I see Snapchat has 30 KB of data. I know this is a small amount of data but is this the amount you would get from merely downloading it, or perhaps setting up an account, or even using it? 2. This was on their old phone. I accidentally tripped over their new phone and on the way down I found in the Safari > Advanced > Website Data section "Snapchat: 44 KB of data". This is a new phone and Snapchat is not found in a search. Does this mean Snapchat was downloaded at some point on the new device and then removed? Conversely, WhatsApp has been downloaded but is not in the Safari > Advanced > Website Data section at all. I know you can delete this data with a simple right-swipe, so - 3. Is it possible to download the WhatsApp app without accruing any website data? Many kind thanks in advance.