How can I control where photos end up when I sync them to my iPhone? I'm trying to have fewer photos on my iPhone (3GS running iOS5), and if possible to have them searchable by naming them.

With this in mind I used Image Capture to download all 500+ pictures onto my MacBook Air (running Lion), then synced my iPhone with iTunes to remove them all. 

(To do this, I made a folder called Empty Folder and put it in my Pictures folder, selected it in the iPhone's Photos tab in iTunes - you can't, for some no doubt magical Apple reason, select any folder that isn't a subfolder within another folder - and synced. Only way I could find to do it, other than wearing out my fingertip by deleting all the photos one by one. I couldn't see any way of deleting a whole 'album' of photos on the iPhone itself or in iTunes.)

I then named all the photos I wanted to keep - 111 of them - and dragged them into another subfolder in Pictures, this one called iPhone Photos. 

I connected the phone again, and in iTunes and the phone's Photos tab I deselected Empty Folder and selected iPhone Photos. 

All hunky dory. All 111 photos are now on the iPhone. 

Except that there are now three albums on the phone: the empty Camera Roll, Photo Library with 111 photos, and iPhone Photos, with the same 111 photos, organised differently. 

What the...?

Is there any way of getting the photos I want to keep into the Camera Roll and getting rid of the extra albums?
To add pictures to the Camera Roll, you have to snap them with the built-in camera (or with a screenshot) on the iPhone.

The Photo Library contains all the pictures, they may be additionally organised in user-specific folders (like your iPhone Photos folder for instance).