Learn Arabic (Modern Standard): وقف السائح حيران أمام الخريطة. - The tourist stood perplexed in front of the map.

It acts as the Hal (adverb of state or condition). In Arabic, the Hal describes the physical or mental state of the subject while the action is happening. Even though it translates like the English adjective perplexed, it functions grammatically to describe how the tourist stood.

Since حيران is the Hal, shouldn't it end with an alif and a double fatha (tanween)?

Normally, yes. The Hal is always in the accusative case, which usually means adding a tanween fatha. However, adjectives ending in the -aan pattern like حيران belong to a special grammar category called diptotes. Diptotes are not allowed to take a tanween, so this word simply takes a single fatha at the end instead.

I previously learned that وقف means stopped. Can it mean stood as well?

Yes, the verb وقف can mean either stopped or stood depending on the context. In this sentence, either translation works perfectly. The tourist could have stopped walking to look at the map, or he could simply be standing in front of it.

Why does الخريطة take the genitive case (a kasra) at the end?

The word أمام (in front of) is a spatial word that creates an Idafa (possessive construction) with the noun that follows it. Because الخريطة is the second part of this Idafa, it is automatically forced into the genitive case.