Yeah, try not to break the weed up too much, I do that alot, I am anti-stem to an obsessive point, and you're right, if the weed is too fine it might get sucked through... the trick here is to find a large-enough destemmed/seeded nug to put @ the bottom of your bowl, and if you have alot of shake throw that on top.
Are you covering the side hole(carb) with your finger/thumb while you're hitting the bowl @ first? I think someone already said that, hehe...
As for tobacco, I don't smoke it anymore as a personal choice, but I have heard some people mix tobacco w/ weed to conserve their pot. It depends on how high you want to get, as tobacco has no stoney properties to it. Out here, I have never met anyone to do so, but weed is abundant in Northern Cali so I know we're spoiled!
good luck and you won't be made fun of here, we all started the same way and smoking alone can be a treat. you can always count on the folx here @ the city for help AND entertainment!

xo~