Landing clearances differ a little by country and sometimes by airports (more by country though). In any case, most contain the same information. First, the tower controller is clearing you to land on a specific runway. Based on the original post here, the controller is advising the aircraft that there is an aircraft in front of them that has been cleared to land. Here in the US, they are required to give the trailing (or preceding) aircraft the type and location on the approach of that aircraft. You hear this all the time at large, busy airports, especially if heavy aircraft are involved or in a case where you have different aircraft of varying weight classes as wake turbulence then becomes an issue and you'll hear the phrase "caution wake turbulence" thrown in to the clearance as well. You should be hearing this with almost all situations involving a 747 in front of any other type of aircraft (including another heavy).
Lastly, typically the aircraft they are pointing out is landing on the same runway as the second aircraft. However, there are also procedures for aircraft landing on a parallel runway separated by less than 2,500 ft (primarily in the US, not sure about other countries).
There's really no defined distance that the aircraft has to receive a clearance by; I think the last post pretty much summed it up (when the tower controller has positive control and no conflicts exist or any potential conflicts are expected to be resolved upon arrival of the cleared aircraft). I've seen aircraft cleared on short final and aircraft cleared miles out; it just depends on the traffic at the airport at that time.