How many is a lot??
Photographs, in general are very small files.
In my photo file, I have 2800 photos, and it takes 7gb.
What really takes the space is video files.
Most any modern laptop will have a dual core cpu and sufficient ram.
I happen to like Lenovo as a brand.
You should have no problem with your budget.
If you can do with 120-240gb or so, I strongly suggest a laptop with a SSD. It makes all the difference in the world for performance.
You will likely find it cheaper to buy a laptop with a minimal hard drive and replace the hard drive with a ssd.
Intel sells a SSD and a migration kit that makes the transition painless.