I'm new here, but I like what I see of the sight so far.
Don't dispare...that is actually a good start.
#1 when sanding watch for sharp "spikes" of dried glass...they feel good.
#2 initial sanding go with a 50 grit to knock down all the high points
to answer some other questions...Rollers from a marine store look like a row of washers stacked together and are made of plastic or metal. They do wonders for knocking out air bubbles.
Mat adds strength, while cloth adds smoothness. To build up strength in a hurry shift the mat 45' degrees from the first layer. The shift in bias adds the strength, third layer of cloth to smooth it all out. So you would add a layer or two of cloth (say 7oz.) then 2 layers of mat, and follow with a layer or two of cloth. Should be bullet proof if the air pockets are taken care of. Also matt comes in many weights. Start with a lighter weight for tight bends, as the heavy weight is only good for flat spots. To get real trick with tight corners mix up some micro ballons (filling powder) with your resin to a thick paste (THINK peanut butter). Smear a layer (a fillet actually) into the corners and lay the cloth over this fillet. No more tight corner to fight the glass cloth and cause air pockets.