Yes, you are on the right track. It is quicker to use a ready made Blank.esp then make your own because they just retain all basic items from the orginal game and they usually are a combination of Morrowind, Tribunal and Bloodmoon. It is usualy what you end upw ith if you do it yourself.
How you make a Blank.esp is to convert the morrowind ESMs to esp with Mash. Then it is load into the CS and one starts deleting everything in game they don't want. It is a time consuming process. If you want to delete a cell highlight the cell name and delete. Once saved it is gone. If you just want to delete cell items highlight all the items you want to delete the push delete. The same goes for dialogue, scripts, etc. for all you want to delete. One doesn't delete items in the Object window unless your sure you don't want it because they are tedious to bring back, these are the items you build your world with.
Then you have what is call your blank.esp.
Once your finished building your world you convert it back to an ESM and then it can only be changed by an ESP.
Did I make it much clearer or did I still muddy the water?