Searching does not always return the best results for a number of reasons but at least users can try and if an answer is not found the many helpful members here are sure to be able to.
The manual is also very useful in many instances (though not all) as it does answer many of the basic questions any new user particularly may need to find answers too.
For instance : The manual will tell you how to use corridors and the differing type duct segments to successfully join them to a room.
There are different types of end segments for corridors and ducts (and doors) to use when joining with rooms or walls which should be used to achieve success in differing circumstances - which the manual explains perhaps more clearly than could be done easily here.
Making a small test level and trying out all the different pieces of duct, corridor, doors, walls and so should quickly return a result in the learning process.
If you are placing anything that needs to punch or cut through a wall such as doors or vents or even corridors where they join walls or rooms - always do so using walls that are placed as part of room segments.
As to the search facility here - Not sure how much work that would be for TGC to achieve a better search result. Its more likely that this could be achieved by the users by using sensible titles and naming conventions/content in threads together with an organised method of managing the forum content - and by keeping threads on topic - something which many users and the Mods are now trying to achieve.
If we can work together the forum will be a better place and all will be able to benefit from any improvements in many ways.
TGC do what they can but users will need to play their part and TGC will expect them too if you want these things. There is a limit to what TGC can do to give you the best of everything - its much a matter of working together towards an end goal of better for all.
"I am and forever will be your friend"