Hi tamifaye and welcome to CC! Let me see if I can answer a couple of things for you!
1- When I level a cake I look at the cake out of the pan. For me there is usually a distinct area that just looks like it needs to go. I don't use the push down method but love my 2.99 wilton small leveler. I found it will tear up the cake if you try to level when the cake is warm-must be completly cool!
2-I would get an oven thermometer. Most oven temps are off and you have no way of knowing it without a thermometer. The crusty top is one reason I don't like the push down method. That top tastes different than the rest of the cake and I find my fillings don't work as well with that top still in place. My 8in cakes take up to 45 min sometimes depending on the recipe I use ( I always use doctored cake mixes-lots of threads on here about that!) You just have to get your oven temp right and learn how long your recipes take to cook. Also measure your batter (charts in wilton yearbook,on wilton site and this site)
3-When putting a cake together, this is the order I put them together: bottom layer,bottom down then filling/icing then flip the next layer over so the tops are now together and the bottom is up. That way you get a nice smooth top to ice! I also like to torte my layers but that is another lesson for another day!
4-Try experimenting with different cake mixes to see which one you like best/that turns out the texture and taste you like. Wal-mart sells a couple of varieties for .88/.89. Maybe once your oven temp is right that might help with less dry cake.