French language Q&A Forum

Bonjour! I have not studied  For over 20 years, and I'm trying to learn the things that I have forgotten, as well as to expand my ability. Could you please answer my question about inverting the subject and the verb when asking questions? I was taught that one would say "Faites-vous vos devoirs?" Or "Fais-tu tes devoirs?" When asking questions. Even asking someone their name I've always known that to be Comment vous appelez-vous? In the formal and Comment t'appelles-tu? In the familiar. Why is this method not followed here in the studies? It has me very confused about what I've learned in highschool and I feel like I'm learning a totally different language. Thank you for letting me ask this question here. I don't know where else to ask it. 

The question and answer: J'ai fini. - Write "I didn't finish." : Je n'ai pas fini
makes me wonder... In English 'I have not finished' implies you are still working on it, whereas 'I did not finish' implies that you are not still working on it (e.g. you ran out of time in an exam). It looks as if the passé composé could mean either of these. Right? If so, what is the easiest way to make this distinction in French?

What is the difference between effets and efforts and why is sembler cited as the "best" answer but the final para uses paraître?

Both si and tellement are used for so.  Are thee interchangeable or is there a preferred context for use?

More and more the Kwizik algorithm resembles a policeman hiding behind a bush in order to catch a speeding motorist. Please inform us if we haven't answered a question. A lot of the time it is accidental!???????????????

I still don't understand why "les" is the answer but not "ses". Please explain, thanks!

In the last sentence I typed "quand ils partent de mon salon !" but "partent de" marked as an error and advised "quittent" or "sortent de". 

Could you please explain why "partent de" cannot be used here as an option ?

For "partir", in the relevant lesson, it is written as: "When used with a place, it will always be followed by a preposition (e.g. I leave from / for  = Je pars de / pour)" Example: Je pars de cette ville.

I would like to know what the " l' " refers to in this sentence:   

Seriez-vous partis si je vous l'avais demandé? 

Would you have left if I had asked you?        

I can only surmise that it means something like: