Learn Turkish: Yağmur çiselese de yürüyüş yaptıktan sonra kahve içiyoruz. - Even if it drizzles, we drink coffee after taking a walk.

The verb çiselemek means to drizzle. By adding the conditional suffix -se and the particle de, it forms the concessive conditional. In Turkish, combining the conditional -sA with de or da is the standard way to say "even if". You could also use bile instead of de here for the exact same meaning: çiselese bile.

I remember sonra means "after," but why is it yaptıktan sonra instead of just yapmak sonra?

To say "after doing an action" in Turkish, you cannot just put the basic verb next to sonra. You must use the structure -DIktAn sonra. This attaches the past participle -DIk and the "from" suffix -tAn (following consonant harmony for yap) to the verb stem, making yaptıktan sonra.

The English translation says "we drink" (a habit), but içiyoruz uses the continuous -iyor suffix. Shouldn't it be the aorist tense içeriz?

You absolutely could use the aorist içeriz here to express a general habit! However, in everyday spoken Turkish, the present continuous (-iyor) is frequently used to talk about regular routines, similar to how we use the simple present in English.

Why is the word (rain) included if already means "it drizzles"?