Learn French: Il sort même s'il pleut. - He goes out even if it rains.

Unlike bien que and quoique which require the subjunctive, même si (even if) is an exception. It is always followed by the regular indicative mood, following the exact same rules as a standard si (if) clause.

How would this sentence change if I used bien que instead of même si?

It would become Il sort bien qu'il pleuve. The meaning shifts slightly from 'even if' (a possibility) to 'even though' (a stated fact), and you are required to use the subjunctive form pleuve instead of the indicative pleut.

Does the word si always contract to s' before a vowel, like in s'il?

No, si only drops its 'i' before the pronouns il and ils. It never contracts before elle or on. So while we have s'il here, 'even if she goes out' would be même si elle sort.

Why is it il pleut instead of il est pleut to mean 'it is raining'?

French does not have a separate present continuous tense using the verb 'to be'. The single present tense form pleut translates to both 'it rains' and 'it is raining' depending on the context.