I haven't used any clamps so far...........
Ya, sew like cloth..... to a point. What I do, once I get the leather cut out, is match up the two sides best i can, use the adjustable groover to give me the parallel line based upon the edge, allowing for a bit excess to be sanded off in the final finishing, then decide which end of the stiching area is best to punch the awl through both pieces same spot. This gives you the starting point on both sides. From there use the overstitch wheel to mark out your hole spots, I mostly use the 5 holes per inch one, and use that to sort out the finish spot. From there I punch the holes with the awl, then start a locking stitch (hook both index fingers, and link together like a chain) with needle and thread, use the awl as I have to to reopen holes to get the needle through, pull the needle through and then pass it back through the same hole, put the tag end through the loop formed and pull tight, then work both ends back and forth tightly to place the lock stitch in the middle of both peices, then move to the next hole. Is hard on the fingers (cuts from thread), but what you end up with, when done right, the holes made with the awl, leather fibers are forced aside, the linked thread is kept in the middle, and when the leather dries, the fibers shrink back to their original position (you won't get that if you use a small drill bit to make holes), literally locking the stitches in place.
Waterproofing, simply use mink oil cream, it sinks in faster and easier without the greasy feeling of the mink oil in the "Dubbin" container, it makes a good top coat.
This is where I go to buy (in person, but they do mail order), all my leather working tools and supplies. Used to be Tandy, but they still have that trade name.
http://www.zelikovitz.com/index.php?...tpage&Itemid=1
I buy remnants there for all my sheath making needs, am going back in a week or two to buy more, PM me if you want me to buy you something in a certain thickness of leather and size, and you can EMT me the cash after, I'll mail to you. Heck, I can supply you with everything you need for tools from there if you have the cash to spend.
Plus, I have a member's discount, so I get from 10-30% off items I buy there.