I use an Aoyue 968. Not a cheap iron at all. I think it has something to do with the cleaning process and tinning.So most likely both your problems are caused by a cheap or faulty iron. A good iron will spread heat through the entire tip. Same thing goes with the tip a good iron will be made of HQ material. If you want to preserve your tip clean it of all the solder after every use and try keeping it plugged in only when your using it.