You already got three identical answers on first two questions, so I'll try to answer on last one.
In general, unless you need to carry some kind of demo product/equipment and/or required to be dressed in a particular manner, try to pack such a way that you have carry-on luggage only. It will advance convenience of travel - no need to wait for luggage or be concerned it will get lost, plus reduced weight to carry around.
I will add on to this since I travel for business very frequently with just one carry-on or one backpack, usually 3D2N
Clothing (on me)
- overseas business trip blazer and matching work pants + undies
- simple round neck t-shirt (Grey or Cream)
- Work shoes
Clothing (packing list)
- 2 x undies (washable or disposable)
- 1 x ultra light polo shirt
- 2 x work shirt + work pants
- 1 x singles + shorts
- 1 x ultra light casual pants
- 1 x minimalist gym shoes
Items (for work)
- company iPad + display output accessory (VGA+HDMI)
- travel adaptor
- 3-in 1 charging cable with data transfer
- thumb drive
- work phone + power bank
- air ticket + hotel + transport booking
- Passport + ABTC card
- travel sim card
Items (personal)
- travel toiletries kit (all 50ml)
- 1 x 120 pcs tissue pack (big)
- 3 x 8 or 10 pcs small tissue pack
- basic medicine kit (with official English explanation)
One cabin size luggage/EDC backpack + 1 laptop bag. All under 10kg
Just a side note, I specifically choose ultra-light or quick nano-dry clothings so that I can quick wash the same set of clothing for longer business trips like 7D or 8D