Is the 747-200F fuel guzzler?
Yes, it is.
Could I find today for next month a B747/200F?
Yes, it's likely
There are B747/400F or MD-11F available in the short term?
NO
Which is the average month leasing rate for a B747/400F?
At least 1m USD
In this scenario if you want to enter today in the air freighter market (I mean the medium/long haul) you have to go with a B747/200F. For a B744F you need to wait at least 8 months.