Awesome present, @rodwha !

If Dominican Seco is your only filler, you'll get pretty mild cigars but they will have excellent flavor. You might want to add in some viso and ligero to spice things up a bit

Re the rolling pin - I use a miniature baker's rolling pin to smooth out the subveins in the wrapper. Not always necessary, but the wrapper I use is CT Broadleaf which has pretty thick veins. Speaking of which, I always cut out and discard the main veins in all my leaves - filler, binder, and wrapper.

@Sir Lancerolot has good advice on moisturizing. What I do is give the leaves a slight spritz with distilled water and store them overnight in plastic grocery bags prior to rolling. For the wrappers, I give them a pretty good dampening so they're pliable and slightly stretchable when wrapping.

Regarding the use of scraps - I don't normally roll them into cigars - doesn't usually turn out well. I like to make pipe tobacco flakes and ropes with them.