If it makes you feel better, arms shipments to other countries remain the property of the US DoD and cannot be sold by the receiving party. Whatever India sent to Russia, it didn't come from the US military.
Yea that's possible, and has been done extensively in favor of Ukraine. However, considering the date differences between the US arms and Indian arms shipments, I think this is about India vying for power on the world stage and the US hedging bets against China.
Pretty sure India is mostly selling Russia's old arms back to them. The new stuff should probably be interpreted as an attempt to build a counterbalance to China in the region (as in deliberate, longstanding US defense policy).
BRICS is a meme. It was a term a Goldman Sachs researcher used to describe developing economies that are worth investing in.
Brazil is a basket case, S Africa is basically a failed state, India and China are rivals, and Russia is eviscerating itself in Ukraine and turning into China's Canada.
BRICS isn't an actual alliance. It's an economic forum to try and counter "first world" domination. India and China have regular border skirmishes in Kashmir why they maul each other to death with clubs.