1. In planning-> detailed monthly activity planning, I specified the project, and generate the report, but it shows all the projects in the report.
Is that correct?

It's a bug => ticket #385

2. In some planning report, I see some cells are empty, some cells with real work hours, and some cells with planned work hours.
I'd like to know how 'planned work hours' are calculated.
And I see number '9.99' shown in the cells. When will '9.99' appear ?
Is that related to capacity (FTE) ? but why not integer.

Planned work is calculated when planning is calculated. The planned work is the repartition of left work taking into account activity constraints and resource availability constraints. Display of '9.99' is a rounding issue : work has been extended to number(5,2) while plannedWork is still displayed as (3,2) : so 10 is stored as nearest value (9.99) => Ticket # 396

3. In planning -> monthly availability of resource report, I see '0.0099999999999998' number in some cells. why will this number appear? what does it mean?
why not show '0' instead?

It's a consequence of previous bug : 10 - 9.99 has been estimated (in float value) to 0.009999999...