If you really interested to learn Thai then its not a big task know. You can get many online source for learning.
Thai lounge is not compulsory for visiting Thailand their several peoples are know English very well. You can communicate them in English.
The Wat Phra Kaew is regarded as the most sacred Buddhist temple in Thailand. I read a great history of Wat Phra Kaew,Buddhist temple.
If you want collect more deteil about Wat Phra then visit this Wikipedia's link.
en.wikipedia.org/wiki/Wat_Phra_Kaew link.