I've made a nice set of Titles for my videos, the style of which are used again and again except that each time I have to re-create the same Titles for a new video.

Is there a way to save them and then import them into a new video rather than having to make them over again?

have you read the manual on titles. There is a section on this

What I had in mind was being able to save Titles that already have Transitions applied to them.

you might be able to make use of the "paste effects" functionality. But no - dont think you can save titles plus their transitions.

Well then, is there a way to import one kdenlive project into another?

Yes you can import a project as if it were a clip.

I want the functionality of a Title Clip that has all of it's Transitions/Effects as it appears on the timeline.

Rendering to a video format is a possibility but wouldn't allow for any modification of transitions or effects that were applied to it.

Maybe I should just create a standard kdenlive project that has only the basic Titles with effect/transitions and then use that as the basis for future projects? It seems most of the titles I create have a similar appearance- only the text changes.

The problem I had with that method was that the project (simple text with fade to black) appeared as 1 rectangle (for the lack of a better description of it) on the timeline with no way to edit the text or transition.

yeah. thats kinda what I thought would happen with importing a project as a clip.

Use the http://userbase.kde.org/Kdenlive/Manual/Titles#Template_Titles_-_User_Defined and the copy and paste effects to do this is probably the best bet.