Yes it does.
No, Instagram cannot use cellular data when it is switched off. The app requires an active internet connection to send and receive data, which can only be achieved through Wi-Fi or cellular data. If cellular data is disabled, Instagram will not function until a connection is re-established.
Yes, but not as badly as you'd think. Although Instagram for iPhone saves larger images to your photo library (usually between 3-4 megapixels), the images uploaded to Instagram are much smaller, 612x612 pixels which use a lot less data -- about 100 kb each or so. Images you see onscreen in your feed are even smaller. As with anything online, the more you use Instagram, the more data you'll use.
Generally, 100MB of data on an iPhone 4s would not be enough to use even if you were only using Instagram and the Whatsapp each month. These apps regardless of regular use or using every few hours would consume a large amount of data, especially if you plan to upload pictures.
Yes it does. More importantly on some devices it consumes your data.
Instagram uses between 2 and 10 mb of data per minute depending on the number of photos uploaded and viewed. Videos can dramatically increase this usage.
No, you don't need WiFi to like a picture on Instagram. You can use your mobile data to access the app and interact with posts. However, a stable internet connection, whether through WiFi or mobile data, is necessary to ensure smooth functionality.
Instagram does exist, and is used, in Argentina.
Yes, it is a good idea to use repost for instagram app
Yes, Internet is required to use Instagram.
Yes, you can use Getty Images on Instagram for your posts as long as you have the appropriate license or permission to use the images.
Download Emoji in the App store and symbols will be integrated into your iPhone's keyboard. You can use those symbols on Instagram.