What are the gas limits for the transactions? By checking some of the transactions it looks like the limit for the gas price is 300Tgas per transaction.
Also is there a gas limit per functionCall action? And if so, what is the limit.
The third question. For example, we have two functionCall actions in one transaction, and the result is Exceeded the prepaid gas error that is actually telling us that the gas was insufficient - is it possible to conclude which action has insufficient gas?
Gas limit per transacton is 300Tgas. Gas limit per functionCall is also 300Tgas.
For example near-cli has a flag --gas which lets you specify how much gas can be attached to the function call.
% near call
near call <contractName> <methodName> [args]
schedule smart contract call which can modify state
Options:
--gas Max amount of gas this call can use (in gas units)
The third question: consider increasing attached gas. BTW, the unused gas is refunded to you. To tell which function call had insufficient gas, you can check your transaction in explorer.near.org (or explorer.testnet.near.org) and carefully read the generated receipts and their results.