reassessed & planned work

What's reassessed work ? and how it's calculed

Reassessed = real + left,
it is re-evaluated work from real input and re-evaluation of left work.

Some times when i calcule planning for an activitity witch valitdated for example on 21/10/2015 to 21/810/2015 (1 day), the system calculate others planned dates , for example form 22/10/2015 to 02/11/2015 !!

If you enter some work, left work is planned depending on resource avalability.

PS: my planning parameter is :" Fixed duration"

If you choose "fixed duration", you should not define work (no assignment), otherwise, task is planned "regulliarly" for the duration.

Can i entry manually a planned date ?

No, because they are planned : you don't plan. ProjeQtOr does.