1. Yes, it is quite a lot infact. In that distance you can scuff the pistons, spin the main and rod bearings (metal-metal contact) etc etc. 2. Tough one to answer. The hydraulic lifters might not drain away all the oil instantly so there may not be an immediate clatter. The oil film left by modern oils just might cause the engine not to completely seize and lock up for some km's. The only clear warning would have been the Oil light. Apart from that, all we can do is conjecture. Let's see what the OP says.