Did Any funnel money into that bank account without it appearing in the ledger, or the warden finding out? How?

Even back then, getting a cashier's check rather than cash doesn't seem smart. Wherever he eventually used the check, could be tracked.

And even with the warden dead, there would be people wanting to recover that money, if they knew about it.

Where was the outside of the hole in the wall? Seems like it must have been on the outside, so why wasn't it spotted long before completion?

And why wasn't the inside of his cell ever checked? For that matter, why was his bible never checked?