Sometimes I have an idea/thought that is definitely Someday/Maybe but I also know some of the tasks to accomplish the idea. Should those tasks be created along with the idea or should it be put off until the Someday/Maybe becomes a current Project?
The answer to the "should" question is ... it depends. The point of much of GTD is to get things out of your head and on to lists. So you do what you need to do to get thoughts out of your head and on to a list.
In my case, if I have an idea that is clearly a Someday/Maybe project, but the thought comes along with actions, I'll go ahead and write them down. But I don't put them into my active lists, I put them in "project support" notes for the S/M item. That way I know the initial thinking is preserved and available when (and if) the project becomes active.
If the S/M thought doesn't come with actions attached, I'll add it to my S/M list anyway, and not spend any further time working out what might be needed. I already know it is something to do in the future, deal with it when the time comes.
When the S/M project moves to active, regardless of whether the original thought came with actions attached, I run a quick Natural Planning Process over it. That lets me flesh out those initial thoughts (if any) and have some confidence that I know what my outcome really should be.
I'm not that into GTD, but adopted some of the techniques. I usually make a rough draft of the tasks that have to be done to accomplish a certain project. This often is the moment when I decide that the project has to go into the "someday" category. If this is an idea I really enjoy thinking about I don't feel like this is a waste of time: if I did not write down what's going through my mind when I think of an idea, I fearing to waste a precious thought.