#9-2
There is no interrogative word there.
Notice that から is not a noun, unlike とき. This is a conjunctive particle to indicate the reason/cause of the main clause, i.e., 僕はのどが渇いた is not a relative(/modifying) clause.
cf.
彼がアイスティーを飲むとき、私はいつもコーヒーを飲む。
When he drinks iced tea, I always drink coffee.
(彼は can't be used here.)
彼はよくアイスティーを飲むから、私は氷を切らしたことがない。
Since he often drinks iced tea, I've never run out of ice.
(彼が has an exclusive nuance here.)
Incidentally, 彼はアイスティーを飲むとき、いつもストローを使う is correct since the subject of the main clause is also "he". The construction here is actually 彼は[アイスティーを飲むとき]、いつもストローを使う, i.e., only アイスティーを飲む modifies とき. In fact, it can be rephrased with アイスティーを飲むとき、彼はいつもストローを使う without changing the meaning at all. This is often called "は rules the whole sentence".
The rest are all OK:emoji_thumbsup:, including #9-3 and #10-2 (yes, your initial interpretations can be correct).