"En" is much more than a simple quantifier in French (some/some of) --- as you already have sufficint examples of that use in French, I'll show you the others.
"Le gérondif" which is "en"+ the "-ant" form of the verb. I can be used with verbs for many things:
When the action is brief:
En ouvrant la porte, je me suis souvenue que --- as I opened the door, I remembered that.
Je l'ai croisé en sortant --- I met him as I was leaving.
When the action lasts:
Prends un café en attendant --- have a cup of coffee while you're waiting.
Elle travaille en chantant --- she sings while she works.
L'antériorité (which means an action that happens just before another in the past)
En arrivant chez moi, je leur ai téléphoné --- when I got back home/on getting back home, I telephoned them.
En la voyant, il rougit --- when he saw ou on seeing her he blushed.
The manner of doing something:
L'enfant se réveilla en hurlant --- the child woke up screaming.
Il marchait en bombant le torse --- he was walking with his chest stuck out.
Je m'en suis sorti en racontant un mensonge --- I got out of it by telling a lie.
Ouvrez cette caisse en soulevant le couvercle --- open this box by lifting the lid.
As an explanation:
Elle a fait une erreur en acceptant ce poste --- she made a mistake in accepting the job.
Il a gâché sa vie en l'épousant --- he ruined his life by marrying her.
Tu aurais moins chaud en enlevant ta veste --- you'd be cooler ou less hot if you took your jacket off.
En prenant des vitamines, tu serais plus en forme --- if you took vitamins you'd feel fitter.
And finally "en" can also be a pronoun (of him/ of her/ of them / it):
J'en suis fier (de mes enfants) --- I'm proud of them.
Je m'en souviens --- I remember it.
Deux ans après, on en parlait encore --- two years later, we were still talking about it.
And then you've got expressions of quantity which have already been explained.
Hope that helps.
Oh and for your other question, "pleures" does not mean "tears", "pleurer" is to cry, and "larmes" means "tears". There are other words for "tears" and you can see them all here:
· 9 years ago