The juice is succulent (I probably should stop...)

When I was a child we called something else "suc" it was fruit syrup and seltzer water. Possibly because finding juice was not likely. Not to be depressing, but it might be a usage that is still in use, I'm not sure. If you want to try it, use a jigger of grenadine and mix with 8 oz of high quality sparkling water. Yummy.

I dont understand, when do you add the ul vs. the ele thingy

I am assuming that from observation when a "ul" is put after the word the indeffenite article the is put before it. I've seen this with words such as ,copiul barbatul, baitul, sucul etc.

sucul

The juice is loose