In the long version (ie any game where both sides get two innings, lasting three, four or five days), the winning side needs to both
a) score more runs overall, and
b) take 20 wickets (unless the other side has voluntarily declared, or waived away, some of the remaining wickets, in an effort to win the game themselves more quickly.
Draws in the long game are frequent because often two strong batting teams effectively cancel one another out- a lot less than 40 wickets fall in the game.
In that game, about 10% of the playing time was lost to rain (rather less than forecast by local fans in Cardiff :) ). The game is designed to allow enough time to ensure a result even with half a day lost.
Also, many drawn games don't lose any time to rain.
PS one source of confusion is the difference between following on (where the team batting second trails the other by more than a set figure- 200 in international matches, and can be asked to bat third as well), and declaring (where the batting team waives wickets). In the first example, the trailing side can still win by making a big score in the third innings then taking 10 wickets in the fourth for a higher aggregate score. Note that in this example the side batting first also bats fourth. Anyone still awake?
PPS I find hurling much easier to watch than G-football, maybe because the lack of a tackle is less of a problem in the former?