Attic flooring 18mm plywood on 9x2 joists

Hi just have a few questions id like to get an opinion on recently purchased a new build and the attic has just under 35 sqm of useable space upstairs iv done a bit of looking in it today and came up with the following

The joists are 9x2 and the spacing between them 22"

The info on the joist is

Kingspan century truss
T01 , timber grade C24
Timber span 12125mm
Pitch 35 degrees
Weight/ply 214kg
Eni 4250-2010
0400/2280/T01

From the top of the floor joist to the bottom of the ceiling truss is 8ft 3"

Insulation is packed between the beams and also then a layer is on top the plan at the moment is to floor the entire room with 8x2 lenghts of 18mm plywood eventually i want to convert this room professionally but for now i want to just floor it for storage im thinking if i floor it now using the 18mm ply this will do when the room is eventually converted were as if i use osb or mdf it will be have to be ripped up and floored again

So my questions are

Will i need a raised floor ?
Does raising the floor on loft legs weaken the floors strenght?
Is 22" spacing suitable to be floored with ply ?

Any input would be helpfull thanks iv attached a few photos below