Change Image upload option

Hi,
We have around 3000 products and every product have 3 to 6 additional images. While uploading image it display image name wise display ( We have changed it to latest first). But it load long time to view the image.
Its difficult uploading and select image.So we plan to separate folder products, banner, informations ( CMS) image ( Not using OC default filemanager options). We tried this format, not working. If same file name upload and renmae and upload. Please advise this. Is there any extensions
And also we delete the product, the product image is not delete. How to identify not used image and delete.

How to acheive this? Is it possible in opencart.