Proportional response by Israel requires more critical thinking than what you have outlined. I completely disagree that Israel should indiscriminately destroy Gaza as if it were WWII again. Proportional response is through the use of its systems to strike at the head and heart of Hamas. Additionally, it will consider its sources of supply and conduct deep operations against its command and control while interdicting/destroying its resources. Furthermore, it will reinforce its position against Syria and Lebanon and prepare for those contingencies. Egypt is a wildcard for Hamas, so proportional response must take that into consideration as well as continued interference from Iran and possibly Turkey.
Russia claims to have hit three ISIS targets in Homs, Syria; 6 other sites also hit (Reuters)
from the article: LIVE BLOG: Day 3 of Israel-Gaza conflict 2012