Your question is not just about whether and if, but also about the correct tense to use and about appropriate politeness.
'I was wondering if...' is a good example of a polite request. Past continuous tense to indicate distance, indirectness (and thus politeness):
e.g I was wondering if I could take the afternoon off', said to a superior.
'I was wondering whether...' would generally precede two options only, e.g. either yes or no. The tense and the use of whether suggests a formal context, perhaps at work.
e.g. 'I was wondering whether we should use the red or the blue heading for the report'
In 2a and b, the tense is less appropriate, and I personally would not expect to encounter these forms. Instead, I would expect 'I wonder', which is a little less polite than the forms in 1 but fine in many contexts. Since it is less formal, whether feels a little less appropriate than if. Thus:
'I wonder if you could tell me...'