I cant access ALL my Icloud photos on my PC?

I need help.

I have 8,000 photos and about 25 GB of videos stored on my icloud. Nearly all have been taken on my Ipad and I have used the option to store them in the icloud which only saves a 'snapshot' of the image on my ipad (each image/video needs to be downloaded when I view them).

Now, I want to be able to download all photos onto my PC (windows 7) but this is the issue I have. Icloud photos (photostream) only stores the last 1000 images on my computer. I can see clicking on the icloud icon on my desktop that the photos and videos are there but I have no way of accessing them or downloading them?

NEED HELP