you should have a couple of mm's movement at the clutch lever, before it starts to engage the clutch.
if you loosen the locking nut on the adjuster, then turn the main threaded adjust out (anticlockwise, looking towards the end of the handlebar)
try the lever a couple of times, and adjust it up till it has 2-3mm bit of free play.
when you want to slow down, just back off the throttle, the engine revs will drop and help slow you down, and use the brakes too.
then if you are wanting to stop, then pull the clutch lever in.
select neutral if you want to sit for a minute or so, then you cane let the clutch lever out, and the engine will idle.
when you are ready to take off again, pull the clutch in, select 1st gear, then slowly let the clutch out and you are away again.
stopping without the clutch pulled in will labour the engine a bit, but shouldn't have done too much damage