The notches were started (I think) on 126 film cartridges. I used to have a link for 110 notches, but cannot find it. Here is the best I can come up with at the moment, just to give you an idea:
Of course, you can't forget wikipedia (and perhaps go to camerapedia):

I've heard the presence of a flash did change the shutter speed even on the most basic models, but I've not confirmed this.

Finding info on the flash adapter has been difficult. When I got home from work I dug out mine - its an Acme-lite 138. Something like this would probably work on your 110, but is a dedicated flash, not an hotshoe adapter. Here is an old ebay listing (it is sold). I have one for my 126 cameras:

I think the unit I got my best friend is similar to this National PW-110 adapter - it is an hotshoe. The one on this page appears to be for flash cubes, while hers is for flash bars, so the model number may be different. As you can see, a plastic "clip" ratchets to clamp it on the camera. On your (and her) camera, since the top is not flush, it will not reach the slot. Also, the clip would have to be modified if the camera stays as-is. I intend to fabricate an extension for her that will plug into the camera socket, and the flash adapter will plug into the extension.

Basically, I will use an old flip-flash for the plug, and probably get an old extender to cannibalize for it's socket ( - to make my own extension.