Can you finish a spell that last such as fire breath and Elemental touch with spell combat after the first round? I have to keep asking DM's if I can do this, but I'm not so sure I have the answer to say so or not. For sure, you can use spell combat and fire breath its first round of breathing fire, but can you keep doing it the next two rounds. If you can I suppose you don't have to roll a concentration check. The creatures are rolling saves each round for it. Then they get walloped with a minus two to hit.
The same with Elemental Touch. Can you use spell combat with that spell after the first round of effects go off till you run out of effects to hit with. Elemental Touch is probably more aft with spellstrike anyway. If you use spellstrike with Elemental Touch I believe you are spellstriking for a few rounds in a row.