Basic luggage for 2 weeks

Hello everyone

I have posted several topics in relation to retiring in Cambodia, which I hope to do within the next year. However I need your help on something that has only just been apparent.

I hopefully am visiting Siem Reap early December for approx 2 weeks, as it has been made available for me to leave work at visit.

The panic is....I want to travel with the bare minimum, no cases, just a backpack if possible. Usually I plan for weeks/months even years, however can't do that as only found out this week I can have December off to travel.....yippee!!!!

Could anyone please list what indeed to bring,...the only things I have on my list are:
Passport incl photocopy
Plane tickets
1 spare set of clothes
Spare glasses
Toiletries
iPhone & charger
iPad & charger
Travel insurance
Rucksack
Camera

Also a few questions:

1. Is the above list missing anything?
2. Any more type of clothes than normal
3. Visa...I am travelling straight in/out of Bangkok, will I require a Thai Visa, or can I just obtain a Cambodian Visa on my arrival in Siem Reap airport, although I will be visiting a friend in Chon Buri in Thailand whilst in Siem Reap before I travel back to Bangkok for a week then UK
4. What vaccinations do I need
5. Any pills I need to bring
6. What travel adapters

Many thanks for any help you are able to give as this is very last minute.....

Howard

-you could take some instant pain relief  pill , just in case the pharmacies are all closed in the middle of the night.

A good small first aid kit with anti-diarrhea meds, bug bites, and pain relievers. 

Vaccinations if you're coming from a developed country you should be fine if everything is updated.

As for visas, if you're traveling to and from Cam and Thailand or vice versa, I had to get visas anytime I entered/exited to the other country.

Oh and you can get away with just shorts, a t-shirt and sandals almost everywhere so you can pack light.

Thank you everyone for your replies. If there are any others on here that can also look at my list it would be great th hear from you, Howie