I use good old fashioned Evo Stik whenever I need to glue leather and it's never let me down yet. With the skin side of the leather I roughen it with some 40 or 60 grit paper before applying the glue to "key" it in. On harder, thicker leathers with a smooth finish to the flesh side I do the same on that side too, just to make sure the glue has a good chance of holding well.
I only ever really use the glue to hold pieces together while I prepare the holes for stitching or riveting. I never rely on the glue to hold the finished article together without the stitches or rivets, but when I have fouled up and needed to seperate glued parts before continuing with the job it has been a nightmare to get them apart without taking a layer off the leather (normally flesh side).
If you are looking to keep your starter kit to a minimum you could also do away with the awl. The awl is the "proper" way of doing the job, but many of us (me included) tend to cheat a little and simply drill the stitch holes with a 1mm,1.5mm or 2mm drill bit depending on what the item and the thread needs. A sharpened piece of stiff wire will do the job if you don't force it. Using a pillar drill or Black and Decker in a drill stand helps keep the stitch holes going nice and straight through the workpiece instead of wandering off to the side etc. This is more important with thicker workpieces as the error in alignment is more noticeable on the reverse side. For working with only 2 layers of 3.5mm leather a steady hand and a good eye should see you do do OK with a hand held drill.
For stitch marking on small pieces like knife sheaths you can make a perfectly usable tool by tapping a couple of panel pins halfway into the end of a hadwood dowel about the size of a pencil. Cut off the heads with wire cutters and simply use the two prongs as steppers to make evenly spaced marks along the stitch line. This is slower than a wheel but better for going round bends with than the fork type markers.
