ecu, lead is not for the novice. It takes quite a bit of practice to become proficient at it, and you are constantly walking a fine line regarding the heat applied to the panel. Too little, and you won't get proper adhesion, too much and you risk warping the panel.
For very minor pitting, such as what is left after blasting away surface rust, consider using a high solid content, high build film primer, such as the PPG "K" series. I haven't done any paint in awhile, and the last I used was K-200. I'm sure their product line has been updated since. There are also excellent two part spot fillers, such as "Evercoat." They mix like Bondo, but are made to replace the old tube dispensed spot putties. If you are familiar with the red goop in a tube, it was essentially very thick primer.
Evercoat is easy to work with, and it sands very nicely, both wet and dry.
This little bit should give you some food for thought.
Question away!
Jeff