Yes the small marking they put on positive and negative come off easily with any kind of solvent. I sometimes put a negative mark with a black felt pen on them. The tab positions are generally the same from one make of cell to the next. If worse comes to worse you can check it with a voltmeter.
As far as heat tolerance, if you use a variable temperature iron set at 600F, there isn't a huge concern with overheating them. Just don't heat them any more than you have to. Don't use one of those cheap 25W pencil type irons, they're too hot.
You want the solder to flow quickly once the tab is heated so you should buff them and flux them before soldering. I use Scotchbrite available from any hardware store. Any non-conductive abrasive will work. Emery cloth can to the job as well. I usually tin them first prior to soldering them to a wire or PCB.