2. How often should I clean my tip on the sponge?
The ONLY time you should wipe that tip on the WET sponge is right after you pull the iron from the holder right before you're ready to solder a joint. That "shocks" contaminants and extra solder off the tip giving you a clean, wet edge with which to solder. Do NOT wipe the tip before restoring the iron to the holder or before turning the iron off. Wiping that tip before putting it back in the holder wipes all excess solder off and the remainder will oxidize down to the iron itself which will then start to oxidize.
4. Can I use sandpaper to clean my board ...... I was told that steel wool is a good thing but i dont want to use it cuz it gets u all dirty. what kind of sandpaper should i use?
Whoever told you that steel wool anywhere near an electronics workbench "is a good thing" is an idiot. Steel wool is a good electrical conductor. Steel wool, as it is used, sheds hair worse than a cat, and steel wool's hair is conductive and gets into places you can't see. A good way to get put on report (a bad thing) in the U.S. Navy was to bring a steel wool pad into an electronics maintenance shop. Keep the steel wool out in the wood shop or under the kitchen sink. Want a GOOD abrasive pad for circuit boards? Get a 3M (Minnesota Mining & Manufacturing Co.) "Scotchbrite" pad, the green ones sold for scrubbing tough spots off your pots and pans. Accept no substitute here, for the off-brands are not nearly as agressive or long-lasting as a genuine 3M "Scotchbrite" pad. Sams sells a massive stack of the things for a song as compared to the price you'll pay at a discount or grocery store. The "Scotchbrite" pad is non-conductive and leaves very little residue. It's also more aggressive than steel wool but not as damaging as sand paper or emery cloth.
However, be careful with "Scotchbrite" in other uses. It can and WILL scratch window glass, so don't use a new pad to clean the bugs off your car's windshield. And old, used pad isn't bad for that purpose since all it's abrasiveness has been pretty much used up.
Dean