I think that's two questions, but the first one is - thanks to TMS' Andrew Samson, a nice quick one: apart from the New Zealand one-Test wonder Richard Jones, who did it for Wellington against Northern Districts in Wellington in 2000-01, there are two others who have taken a wicket with their only delivery in first-class cricket. Jones was preceded by Basheshar Khanna, for the Punjab Governor's XII against Northern India in Lahore in 1927-28, and Manohar Agasti, for Vidarbha against Railways in Yavatmal in 1985-86. Adam Gilchrist took the wicket of Harbhajan Singh with the only ball he ever bowled in T20 cricket, to round off his final IPL game, for Kings XI Punjab against Mumbai Indians in Dharamsala in May 2013.
Chris Gayle is actually second on this particular list: he has scored 920 runs in T20 World Cups, including two of its eight centuries (no one else has more than one). But there's one player with more runs than him, the only man in four figures: Mahela Jayawardene made 1016 runs at the T20 showpiece. His fellow Sri Lankan Tillakaratne Dilshan lies third, with 897, but lurking in fourth place is the man likely to top the lot of them: Virat Kohli currently has 777 runs.
Kepler Wessels played 24 Tests for Australia between 1982-83 and 1985-86, then 16 more for his native South Africa between 1992-93 and 1994. The only bowler to dismiss him for both countries in Tests was Courtney Walsh, who had Wessels caught by Larry Gomes for 61 in Brisbane in 1984-85, then had him caught by Brian Lara for 74 in Bridgetown in 1991-92, a dismissal that set off South Africa's collapse when in sight of victory in their comeback Test.
The Australian legspinner Clarrie Grimmett did indeed take 44 wickets at an average of 14.59 in what turned out to be his final Test series, in South Africa in 1935-36. Although he was 44 years old when he took those wickets, his omission from the 1936-37 and 1938 Ashes series was a cause of controversy for many Australians, especially his long-time spinning partner and friend Bill O'Reilly.
The leader here, given a minimum of 20 innings both home and away, is England's Chris Broad: helped by a superb Ashes series in Australia in 1986-87, he averaged 57.44 away from home, but only 26.13 in England, a difference of 31.31. In second place - or on top if you insist on 1000 runs home and away - is the West Indian Darren Bravo, with 50.40 away and 26.78 in the Caribbean, a difference of 23.62; seven of his eight Test centuries have come away from home. Others with a difference of more than 20 in favour of away Tests are Sidath Wettimuny of Sri Lanka (21.76), England's Jim Parks (21.51), and the Indian pair of Mohinder Amarnath (21.42; only two of his 11 Test centuries came in India) and Sandeep Patil (20.43).
Steven Lynch is the editor of the updated edition of Wisden on the Ashes