Good news - Workspace email already supports many of these features. The details below are working in the Classic View (can be toggled between Updated View/Classic View in the upper right of your screen).
1. To flag an email, first select it by clicking the box to the left of that particular email. Then go to the "More Actions" drop-down and choose "Flag". You can also arrange for this to be in the upper menu of icons by going to Settings on top (in the row with Check Email), then Display Settings, then Action Bar. You can keep up to 6 icons on that bar.
2. You would need to move to an Office 365 plan for this feature. The pop email is not able to perform this function.
3. When composing your email, you can look to the end of the formatting bar and find the option to add emojis to your text. (Icon with smiley face) Of course, if you search for "keyboard emojis" in your browser, you'll find extensions for the browser that will allow you to use emojis in any view.
4. While I haven't figured out a way to color the folders, you can set a color for various senders as they come into your mailbox. Once again go to "Settings", then "Message Highlighting". You can create rules to draw attention to your senders with a choice of colors. I find this helps me quickly locate vital contacts.
Hope this helps.
TLH - GoDaddy | Community Moderator Supporting you at x.co/247support