In my immediate mode GUI I achieve some pretty nice font rendering, dynamic geometry for the whole UI is created each frame:
I create quad lists for the text and update a vertex and index buffer each frame. I originally looked at using distance field fonts but i found it hard to achieve the same quality of rendering. The bitmap font sheet was rendered with the Angel Code bitmap font tool. I've added in some GUI elements that use the different font effects such as italic and drop shadow.
The quickest solution would be IMGUI as suggested. I was never convinced it looked that great though and had limited skinning possibilities. I could be wrong though. If my understanding is correct and you wanted to ship the console with your game, it might be better to roll your own.
It's great because it's immediate, I don't have to convey the information about what properties I want in the property control using attributes (as in the style of C#) because I just do or don't give them in the GetProperties() method. I also don't have complicated macros because I just don't need a reflection system.
Are you actually making a game or a demo that requires these non-trivial entity hierarchies and multiple components of the same type? I integrated bullet into my entity-component system the most simple way which was one rigid body component per entity and one collision shape per component and i've yet to require anything else. Point being, just do what you need to do. There shouldn't really be any of these what-if scenarios until you actually need them and then the become scenarios and not what-ifs.
You might also consider using a pick buffer which is a render target where each pixel contains an ID that is the object that covers that pixel. Therefore sampling the pick buffer under the cursor gives you the object the mouse is over. This doesn't solve box selection though, but is a simple way of doing it that doesnt involve alot of projection/unprojection. Note also that its particularly good for picking terrain, where typically you don't want to be doing ray triangle intersection.
A reasonable compromise is to store a set of 1-bit flags on each entity, which tells you which components are attached to this entity. If you need to retrieve the component you'll still need to search for it in the relevant component array, but at least testing for it's presence is now cheap.
Sure that would work. I can't think of any occurrences where i've wanted to see if it has a specific component without actually wanting to do something with it though, not personally.
I decided to take the memory hit and set a MAX_ENTITIES that my engine can support and block out arrays for MAX_ENTITIES for each component. This way each entity is basically a column in the table and doing checks for "does my entity have X component" is just a case of checking the component at the same index as the entity. Ofcourse you will have unused slots in the array but you are also never left wanting as at any point its possible to turn on a new component for an entity by enabling a component at a given index without the cost of an allocation etc. I believe it is also popular to have a bitfield in the entity to discern which components are enabled for it.
Each subsystem iterates over the components checking components[x]->IsEnabled() before processing them.