I have never used Legacy but it sounds like you are asking for something that I use all the time with Reunion.
If you need to enter a source, there is a standard "fill in these boxes" format. You can add or subtract any of the boxes you desire to change, using the variety they give you...or one you make up. And, if the boxes just don't work for the situation, there is a "Free Form" mode that you can choose. Then you type it up as tho working on a blank piece of paper.
The equivalent of "Event Clipboard" sounds like something I do all the time also. For example, if my main source for the local paper is Aurora Beacon News, I put that in from the formatted section as in above. Then, in the memo section, I put the date of the issue, any identifying info such as "Marriage Announcement", and the page number such as "Page 14". Then you highlight that entire line, "Copy" it, and go to the next place you want that same citation. Click where you want it (the next empty source line), and "Paste" it in with a "command-v" stroke.
If you should come upon one place where you just want it to say Aurora Beacon News without the same additions in the memo box, click "command-r" and it will be there.
It seems to go well and easily, but, as I said, I have not used Legacy to see whether it is better, worse, or about the same in ease. Kristy