Lauderw55, yes, you need the lam to fill the void. I have always used Smooth On epoxy for this job... never tried Titebond. I'm not saying it wouldn't work, just that I've never done it. I have a lot more trust in Smooth On for stuff like this.
No heating and bending needed prior to glue up, so long as the pieces are thin enough and able to bend.
I have always used a bandsaw, but I suppose careful use of a good handsaw would work as well.
Regardless of what saw you use, you will need to find the lam thickness that suits the kerf left by the saw. Here's an easy way to do that...
Make or buy a pair of tapered lams that taper down to almost nothing. I usually kerf in about 10-12", so I make those taper lams about 18-24" long, depending on degree of taper. I'll tell you why....
After the kerf is completed in the bow/blank, insert the tapered lam into the kerf sideways, perpendicular to the limb, at the bottom(where the cut ended), and slide it in just until it gets snug. That is the exact size of your kerf, but you need room for glue, so back the tapered lam out just a little bit, until it loosens up just a weeeeee bit, and mark it. Cut it off at that mark. During glue-up, it will be inserted into the kerf until that end, the end you cut, bottoms out in the end/bottom of the kerf. No gaps. No voids. Perfect glue lines.
Start clamping there, at the bottom of the kerf. It will help hold the pieces in place as you work your way toward the tip with succeeding clamps.
This picture is of such a kerfin', but I doubt you'll be able to see it in the picture. I could take a close up of the kerf if you like.