Bro,
IMO, its best to travel without the hassle of a tour group, as you will not be on a schedule to "go here", "go there", "7pm meet at lobby to go makan" etc.
What we did in SR was basically booked into one of the hotels (found online) and did our own thing. You can ask your hotel for tours and prices to Angkor and also a separate River Cruise to visit some fishing villages. These temple visits usually go for about USD20 (if my memory serves me well) a day per person. This will include the tuk tuk and the guide - food, however, is not inclusive.
These prices, however, do not include the entrance fee (payable daily or as a package of three days). The guide will be exclusive to you, and can be quite well informed about the temple's history and such. Tho I have to honestly say that after visiting 4-5 temples, the words coming out of the guide's mouth just floated above my head.
Bring plenty of water and wear super comfy footwear, as you will be doing a looooooot of walking.
Camera wise, best to bring both, even tho the temples are better captured in WA. And if you have a tripod, bring it along too, as there will be a spot where photographers will clamor over as the Angkor temple gets hit with the setting sun rays. (Ask the guide, he will show you where)
They would also have some dinner-cum-cultural shows that starts at 7pm and can offer you some good photo opps.
Weatherwise, not too sure how it will be, as some have said that it can get quite warm. My trip there took place in October last year and it rained cats and dogs. Heck, SR was even under 12-30 inches of water in some parts of town. So bring a raincoat.
Hope this helps.
