Don’t replace the drive band with a leather band. My antique wheels used cotton string bands … about the size of #5 crochet thread. Take a block of beeswax and wax the band to help give it a grip. There’s a special flat knot to use so the knot doesn’t ‘thump-thump’ over the whorls, but if you don’t mind the ‘thump’ a square knot will do.
The wheel is a ‘double drive’, meaning the drive band is one long continuous band that goes around around the flyer whorl, down around the drive wheel, up around the bobbin whorl, back down around the drive wheel, and then up and tied off. It will naturally cross.
The configuration you are talking about usually occurs on electric wheels that only spin in one direction. The drive band needs to cross to get the flyer/bobbin going in the other direction. With a treadle wheel, the direction of the drive wheel is controlled by you! It will spin in either direction.
The tension (control of how slow/fast the take up of the yarn) of this type of wheel usually is on the side opposite the orifice. The knob on the side should turn allowing the flyer assembly to move up & down or perhaps it is like the Kromski Minstrel and the long maiden on the off side allows the flyer assembly to move up and down. When you put on the new drive band, make sure the flyer assembly is in the lowest position because your drive band will stretch over time.
How wonderful you have a husband that supports your spinning! (I have one like that also … )
Best thing you can do right now is (after cleaning and oiling the wheel & putting on a new drive band) is to just sit and treadle the wheel. Don’t be a speed racer!! You want to be able to just have the drive wheel turn at a nice slow & steady pace. Don’t be afraid to use your hand to get it going again. You’ll want to be able to stop the wheel with your foot.
Don’t be afraid to ask questions as you get more comfortable with your wheel.