Well, yes. That is the purpose of an escrow provider after all.
However, any escrow agent worth using should be willing to provide contact information:
Name, address, phone number, email address, etc. With a well written escrow agreement they should be liable for loss or theft of the bitcoins.
Yes. If you are going to use an escrow provider, you should definitely choose one that you feel is trustworthy.
This says a lot about your moral character. Personally my honor is worth much more to me than 100 BTC. There are other escrow providers here on this forum that have also been reliably trusted with more than 100 BTC.
This is not true.
When a 2 of 3 multi-sig transaction is signed, it is very clear exactly which addresses were used to sign the transaction.
It doesn't matter who the BTC was sent to. The escrow provider should only release escrow to an address provided by the intended recipient. With a transaction that large, it would be best for the escrow provider to require a signed message from the recipient that includes the address, so that they can prove that the escrow was indeed released to the appropriate address.
Of course you could. The escrow provider can't betray someone without getting a valid signature from the other party. The second signature would indicate who the thief is and who was betrayed.