Before I buy, is there an IP Gallery Demo?

If not can someone provide a few links where I can look at a few good ones.

Additionally does the gallery have a picture watermarking option?

IP.Gallery is in use here on the IPS Company Forums so you can browse them on here. Also, the Gallery does have an Image Watermarking option, I believe.

Watermarking, yes.

You can use the Gallery here or on IPS Beyond as a generic demo.

The watermarking option, is it easy to use?
I have a PNG image already made, when I purchase the gallery is it easy to install?

I am not looking for a mod, too many hassles when upgrading. The longer I use IPB the more sure I am that mods are a constant struggle with upgrades. I prefer clean installs fully supported by IPB where I do not have to worry when I upgrade to the next release level.

The last question (sorry to ask so many)

I used to have an upload script on my site that watermarked, cropped the image to a specified size and dramatically reduced the size of the image. I was amazed that to the naked eye I saw very little image degradation, yet the kb size was significantly reduced.

Can I specify to reduce the size of the images uploaded to the gallery?

My last site had 80 GB of images and that would have been totally unmanageable with everyone uploading 1-2 MB sizes. With the script I had these huge image sizes were always reduced to under 100 kb's.

Yes, Gallery supports thumbnailing of images and watermarking.