I am very new to Ethereum.
I am wondering once validators are selected for a committee, does every validator have equal voting right? Or their voting rights are weighted by their deposit balances? Thank you!
Yes, all attestations (votes) by validators are equal.
Each validator needs a deposit of 32 ETH. There is little benefit to depositing more than 32 ETH for 1 validator. For example, if you have 64 ETH, it's more beneficial to run 2 validators.