Lets get the safety bogeyman to sleep first.

this is not a problem in any of the tourist areas, The UDA take great care of you as the tourism industry could not cope with a dangerous situation. I have been many times to Uganda, and am going again over December/January wiht my wife. I do not care about me but I do look out for her and would not take her if there was any thought or possibility of putting her in harms way. Having said that of courwe any journey is not without some risk and I would not advocate going on foot into certain parts of Kampala after dark. You will be travelling with a responsible tour guide and they will take good care of you. There are warnings of the far north of Uganda but you will not be going there. Rwanda is an easy living country as is Uganda and the people in both are some of the friendliest I have ever met.

Right gorilla trekking. Two main places, Virungas in Rwanda and Bwindi in Uganda. The usual group size for trekking is 8-10, never more than the number of Gorillas you will be visiting. Permints cost US$500 in both countries and are booked up wel in advance. I would suggest you secure these asap as Dec/Jan are peak times. Ten days is just enough to get to both countries/gorillas by road from Entebbe, the airport for Uganda. Fourteen would be better.

Lots of good tour companies in Uganda operating out of Kampala at all levels of budget. Start planning now.