Many heads are better than one
(Note: the following is only a half guess at this point in time)
Like manufacturing, each project has a specific amount of research hours needed for completion. Unfortunately, research hours are not as easy to ascertain as manufacturing hours.
Each scientist allocated to a project is able to put in one research hour towards the completion of the project. Then for every hour of research time, each scientist contributes one hour towards research.
Once all the research hours are put in, the project will be declared a success at the end of the hour. (Or was it day?)
As research topics require many hours for completion, it is best to have large teams of scientists concentrate their efforts on one project at a time.
Start your projects
New projects appear on the new research schedule whenever their prerequisites are met. For most alien artefacts, this is merely to have a physical sample of the artefact in storage.
A quartermaster may occasionally sell off the last remaining artefect by accident before the science team can extract enough data from the artefact to begin the reverse engineering process.
In order to minimise the damage and prevent sending the assault team on a suicide mission to retrieve another artefact sample, scientists are able to extract all necessary data from any alien artefact at the commencement of every project. Therefore, it is advised that projects should always be started as soon as possible. Science personnel need not be assigned to the project for the data extraction and should continue to focus on topics of a higher priority.
Selective Alien Abduction
(Or how to keep containment lean and mean)
About the only few tips I have are these:
Your alien containment is restricted to TYPES of aliens, not total numbers, AFAIK. Since there are only a limited number of types of aliens, you 1 alien containment in each of 3 bases is more than enough for all needs.
Some aliens do not reappear if researchd. Ie the X-com command says "Well, we've got enough of those, let's shoot them and sell the bodies"
In the case of live aliens, you might NOT want to start and not complete research projects, for the above reason.
Build a dummy alien containment and send everything you don't want there. EVERYTHING. (suggest you only do things like this AFTER you've finished researching Cydonia or Bust)
Bring an autocannon with explosive ammo on every mission. Since you can check an alien's type by just standing on him and picking him up, you can just toss unwanted samples into a corner and get quick and easy kills.
The key to keeping your containment lean and mean is to be selective when capturing your aliens. This can be done through judicious use of the Mind Probe and by examining each unconcious alien for signs of their rank. Redundant aliens should immediately be eliminated through whatever means the field commander sees fit. Otherwise, scientists will have to waste time interrogating aliens in order to make space in containment.
There are only several aliens of great importance. A random live alien, a navigator, a leader and a commander. Note that a commander can provide the same information as a leader.
The navigator allows scientists to assist in further understanding hyperwave technology, and it can also be used in place of the random live alien if you have not captured one already to ascertain the alien origins.
The leader and commander are required for assisting the scientists to locate the source of the alien invasion once the origins have been determined. Not before - after.
Additionally, to further research into the field of psionics, scientists need a Sectoid leader or commander, or an Ethereal of any rank. To cut down on redundancy, it is recommended that the field commander attempt to abduct a leader, commander or navigator from either Sectoid or Ethereal crews.
All other aliens can provide some information, but are otherwise of little importance - although they can provide interesting but not immediately useful information. Alien soldiers in particular are heavily redundant.
Research - the smart way, not the hard way
(Discussion of the pros and cons of scientist by numbers (in groups of fifty))
Summary - Live Aliens:
Soldier = useless except for "Alien Origins" Engineer = gives info on Alien Craft Navigator = gives info on Alien Mission Types (eg: Alien Harvest) and extra research (Hyperwave Decoder) Medic = gives autopsy info that you haven't got yet (broken in Xcom TFTD) Leader = late game info (plz fill in) Commander = late game info (plz fill in)