If We Could Try This - Conditional

Each verb here is in the Present form. It does not matter whether we put the 'playing' clause first, or the ' if ... rain ' clause; the overall meaning of the sentence is the same.
Answer 2 is also valid ~ as a more general rule ('if rain, no football') rather than in any one single situation.
Answer 3 might be how you could describe your thoughts later, looking back on the time while you didn't yet know if (or when) the rain might stop, and whether you might still get a game.
Answer 4 is the only one which would never make full sense.

This is a simple sequence with a 'trigger' ('if--clause) in the Present and a possible result in the Future.

'If one thing WERE true, something else WOULD follow' : this is the pattern. In this case there happen to be two parallel conditions (one each for her and for him).
This was one of the classic popular love-songs during the latter half of the First World War.

'If I WERE ... I WOULD (or wouldn't) ... ' : This is a very similar sequence to the one in Question 3.
This situation is based on a classic story about the kind of answer some people might expect from an Irish person. As such, we suspect it has a very tiny element of racism in it ~ but like all jokes, it is meant in fun, and the humour (if any) lies in the alternative logic.
We are aware that there are traditions all over the world where if people in one country want to tell a slightly silly story, they pretend it is about one of their national neighbours who is supposedly stupid. Perhaps in your own home culture, there is a tradition of making jokes about the people just across the border? (The French used to do this about the Belgians, for instance.)

Another pair of simple present verbs (though implying the future). This statement has the feeling about it of a 'rule' or 'truth' in life generally; such things are usually expressed using the simplest tense sequence.

Answer 1 is wrong because 'I may' is the wrong way round for asking a question. Any of the other Answers is good, but No.2 is probably the best. Note that the verb in the 'if'-clause is in its Present form, even though the decisive situation has not yet started.
Answer 3 is slightly old-fashioned and pedantic, but very polite; Answer 4 is clear and simple. Here again the 'if'-clause is in the Present (and not even its Continuous/Progressive form).

In an unlikely situation such as this, we express 'how far away it is from reality' by putting the 'if'-clause into the simple past tense (in this case, a common irregular verb, too). The unlikely result then goes into the Conditional form. ('If I did X, you would do Y.')
The version in Answer 1 is clear and possible, but somehow feels as though it is being too direct and persuasive. The odds of winning the National Lottery in Britain are usually quoted at around 1 in 14 million (which would be about 4 winners each time, if every one of the 60-million or so in the country held one ticket each).
Answer 2 begins with an inappropriate tense: there's nothing 'continuous' about a Lottery win ~ it either happens (once) or it doesn't.
Answer 4 is a 'false start' since this is not how we form the past tense of 'win'.

In a positive answer, 'it is ... if we do ... ', which is splendidly simple. Our next Question offers a similar situation in a more uncertain form, using subtler tenses because the suggestion is less confident.

A positive answer here would be 'They would ... if we did ... '. The speaker is making a more indirect suggestion.
Answer 3 is acceptable and even more hesitant; probably not a structure you need to master at this stage, but it could be helpful to recognise when native-speakers use it, as a way of subtly expressing doubt or reluctance about a suggestion ('I suppose we could go all the way to London with you, if you were really sure that's what you wanted to do ... ')

This is the standard ~ and perhaps slightly 'dramatic' ~ way of expressing regret over commitment to something in the past, which has now left someone in a difficult situation. Note that we invert the verb (instead of saying 'if I had known', it becomes 'had I (only) known ...').
None of these other Answers works properly in English, though the meaning would probably be understood.
We hope you feel more positive about handling these ideas, and the language for them ... 'If you're worried about it being complicated, don't be!' A lot of the time, simplicity is more important than subtletly for getting the gist of a conditional message across.