1 if all parts are hot, it shouldn’t matter. As soon as you touch anything with the solder, it should distribute evenly around the pad and component.
2 you just feed it into the joint
- If you are not quick enough, the flux in the solder evaporates and it becomes sticky. At this point, clean it and start fresh. Other possibility is that you didn’t heat part and component enough for the solder to flow
It makes the tin non sticky. Heat up a blob of solder for a minute or so to evaporate the flux and then try working with it.