Photos app queries for iPhoto users
So I know there is this movement of transition from the iPhoto app to the Photos app in all Apple platforms - my query is that many people (especially those with multiple devices) have limited iCloud space (only 5GB) therefore I am still using iPhoto to manage my photos between devices. Perhaps I am understanding this wrong but I have the following which require some clarification of:
1. Does "Photo stream" still exist in Photos?
2. Do the photos / videos take up space in iCloud? In that case 5GB would not be enough in most cases for all users.
3. Will iPhoto still stay in the future updates? Is it a must to transfer all photos to the Photos app across my Mac, iPad and iPhone?
4. How does it work if I am still using iOS 7 on my iPhone? (as I'm using an iPhone 4 which doesn't support iOS 8) Does that mean photos / videos I took from my iPhone will not update in my other devices using Photos of iOS 8?
Thank you for your help in answering the above.
OS X Mavericks (10.9.3)