Yes, you can use as many block and galleries on one page as you like.
Yes, your client can add up to 10 photos per gallery.
Photos are added by selecting any HQ photo on the clients computer. The photo will be automatically resized, trimmed and further optimised for publishing on the site. Thumbnails are also created automatically.
All automatic photo preparation will be done before uploading, so slow connections are no problem either.
The photo upload routines are 100% foolproof, clients are not able to publish 10 megabyte photos that will slow down the website.