There is only 2 seasons in Thailand, hot and hotter.
If you are not used to that kind of weather, I would advise you to pack only clothing to go there and to come back, buy the rest of your clothes in local shops. They will be a lot more breathable and dry a lot faster with the sweat.
Drop the Nissin and tripod, unless you really plan on using them for the architectural shots.
For daytime use, XF 23mm. Or the 35mm, but I feel the 35mm equivalent is more versatile as walkaround lens.
For nighttime, XF 16mm. I shoot mine at night at ISO 6400 at 1/30 easily. It's never too dark for this combo. Great because Bangkok comes alive after dark.
For portraits, XF 56mm or 90mm. Makes a good walkaround combo with a 23mm. 90mm is weather sealed, might come in handy.
That's all I would take to be honest, Thailand is hot and humid. More weight, usually just means that you get tired sooner and sweat more. I was in Thailand when I was just a beginner photographer. Most of my gallery here are pictures taken with a Canon 500D and 50mm equivalent and a 200mm equivalent. I took 4 lenses, I usually left 2 or 3 at the hotel. http://www.tomhenderix.com/thailand/
