MSCI (Morgan Stanley Capital International) all world index, is a stock market index of 1612 stocks from all developed markets, 23 countries (doesn't include emerging countries like India). Here is a fact sheet on MSCI all world.
MSCI All country world index(ACWI), includes both developed and emerging countries. Check this fact sheet.
Yep, both these indices should ideally give you an indication of what is happening in the markets around the world.