If you are a couple, i suggest you to go in 自遊行mode. Because Bangkok has BTS & MTR now, it is not difficult for you to travel around. Just buy a tour guide book (e.g.胡慧X) in book shop and follow its recommendations. For the language problem, English is enough. I went to BKK two times before and also in 自遊行mode. I suggest you to choose Wing X Travel (X ON Travel) as their service ok and they willing to refund the whole amount to me during the close of the airport last year. I just returned from BKK last week.
For 串燒, i recommend you to go to a Japanses restaurant at Central World (7/F), not expansive
