It isn't unusual for the number of notches on the snails to be unequal.
As for adjusting the chain, that's covered on page 70 of the Owners Manual but I know there are folks who don't have one so I'll touch on the high points.
For tools you will need a pair of pliers, a 18mm, 24mm and 30mm wrenches or sockets. A large adjustable wrench (Crescent Wrench) that can be opened up to 30mm or 1 3/16" can also be used. A small soft mallet is also handy to have.
A felt tip pen is also handy for marking the present pin location on each snail.
With the bike on the center stand, first loosen the brake rod nut at the rear of the brake arm.
Remove the cotter pin (split pin) that goes thru the castellated nut.
Loosen (but don't remove) the castellated nut, the brake anchor nut and the large hex nut that is against the right side snail.
Rotate the snails on both sides of the bike an equal amount in a counter-clockwise direction to tighten the chain.
With the bike on the center stand, the chain should have about 2 inches (50mm) of movement total when pushed up and then pulled down about midway from the two sprockets.
If the bike is resting on its sidestand, this 2 inches will be reduced to a little over 1 inch of movement because of the location of the swing arms pivot point.
Once adjusted, lightly tighten the brake rod adjusting nut to expand the brake shoes tight enough to keep the wheel from turning.
Tighten the large hex nut, the brake anchor nut and the castellated nut (in that order) and reinstall the cotter pin.
Adjust the brake rod nut to provide a suitable amount of brake pedal movement.
When doing this have the bike on the center stand and rotate the wheel. It should rotate freely until the brake lever is depressed.
I like to check the wheel alignment when I'm doing a chain adjustment and IMO using a long straight stick or pole (aluminum tent poles work nicely) that is about 1 foot longer than the distance between the axles is about the easiest way.
Using a aluminum tent pole I snake it down under the center stand legs. Pressing it against the side of the rear tire so that it rests ahead and behind the axle I look at the distance between the forward end and the front tire (with the front wheel pointed dead ahead).
I then check the other side of the rear wheel to the other side of the front tire.
If it is an equal distance on both sides, the rear wheel is aligned.
As I mentioned, it is normal for the rear snails to be in slightly different places and if you use the pole method to align the rear wheel, don't worry about it.