How do you handle static images

I’m finishing up my image hosting service and would really appreciate your feedback! It’s not live yet but if you have a personal blog or a company could you please help me out?

1. For static images (i.e. images in blog posts, header images, etc) do you host on the cloud? Or are the images part of your bundle you upload?
2. If you don’t host in the cloud, why not? Do you care?
3. Do you resize raw images before using them on your site (i.e. for a thumbnail to increase speed and decrease bundle size) or do you do it in CSS?
4. Do you share images with your team, and if so does this get annoying (keeping track of images and image sizes)
5. Do you use a CDN?

I’ve built a service where a team member can drop an image into a "drop images here" box and they're automatically uploaded to S3. I then provide an easy way to customize the image sizes, provide the S3 link, and provide a download link. I did this b/c my designer was always making HUGE files and sending them to me in Slack. So I had this manual process of downloading the image, resizing the image several times (header image, thumbnail, mobile), uploading to S3, THEN getting the S3 links. Now he can sign on to my site and drag and drop his huge images to our bucket easily, I can retrieve them and resize them simply by typing the size I want, grab the URL, and I'm good to go.