Tilt your bars forward some (so they are inline with the fork or straight up and down or between there somewhere), brake pads won't help your braking issue... Clean the rims with Simple Green, sand the pads on the bike down slightly and see if that helps. The brake cables should all get a shot of Tri-Flow down them to help them move better.
Lower your brake levers so they aren't sticking straight out.
For really good braking, switch the rims to a chrome plated version. There is no question in this world that chrome provides the best braking surface in the world in dry conditions.
Tricks / How-to's are available all over include
www.bmxtrix.com - do some reading.
Don't measure your bunnyhop height, just practice them. If you know you can clear 20" and no higher, then you will never clear that 24" ledge. If you stop measuring and just start doing it, you will clear things that you never got over before.
Make sure you are bunnyhopping correctly.
No, it does not appear to be a dept. store bike. Looks like a $200.00 entry level bike from a shop.
Finally: DO NOT SKID! Okay, occassionally, but you wear through tires way to quickly if you do it all the time and good tires (not crap ones) will run about $15 each. Give me a few hours of skidding and I could wreck my Primo Walls... not cool. You definitely should be able to lock you rims up though and stop on a dime.