Hi Saidjibril,
Welcome to Tbot!
Regarding your questions #1 and #2,
I think that you’re confused about what “source” and “target” mean.
“Source” means the language from which you’re translating.
“Target” means the language into which you’re translating.
For instance, if you are translating from English to Spanish, the source language is English and the target language is Spanish.
“Source” and “Target” have nothing to do with people.
Regarding your question #3, Tbot can’t handle 3 languages like your example at the same time.
For more details on how to use Tbot/Tbot commands, go visit: http://www.microsofttranslator.com/user/bot/
Hope that this is helpful. --Takako