Different cassettes model have different chassis height based on HP. 2-2.5HP falls between 22-28cm height. Anything more than 2.5HP typically range from 27-30cm in height. There are slimmer cassettes with 16-23cm height but those are not in this market yet.

For cassette, my take is the ceiling height 11' minimum with a 40-50cm drop for allowance in clearing beam height in situations where beams criss-cross installation location. Meaning that for some locations with beams criss-crossing, the pipes have to clear beneath the beam so the drop must accommodate that. The crucial one is the water outlet which usually goes to the nearest possible outlet either an outside wall (easiest) or toilet. The drain pipe must drop in a gentle slope and hence they don't necessarily have to be drained where the compressor is if it's not the nearest. So the false ceiling must take drainage slope into account.

1.5hp instead to 1hp.
The rest follow your location 

The option is remain your idea, then can choose1.5hp or 2hp to switch on diff. Place

Just 1 2HP for dining and living together, move the 2HP at your photo a bit more center.
Have the blower unit blow towards you are not a good idea.
Last time I also like this, but it is very cold.

Bro from this, i found out Daikin / York / Mitsubishi for 1 HP

Daikin is at 10.38 EER
York at 11.41 EER
Mitsubishi at 12.79 EER

which means Mitsubishi power consumption lower... and will save more am i right??

panasonic then,
i do comparision between EER for few brand below already
Hitachi 12.80
Panasonic 12.56
Daikin 12.14
York 11.66
Mitsubishi 11.08
which means hitachi more electric saving (assuming all used in same condition and hour and etc)

dude it suppose to be different what... what kind of question u asked ? =.=
go read SEER rating.. and how to calculate
huh? dont understand u..
i tested yesterday night... with 25 degree... comfortable level.. dont owned a R22 before so i dont know R22 cooler or R410a

oh my bad... actually i do 2 time of calculation

as u know inverter there are variable power / btu output..
the 1st one i calculate using the MAX power
and for the 2nd i calculate at the spec btu output..
to make it clear example as below:-

Daikin 1 HP R410a

btu/h 8,500 (4,100 - 10,900)
power consumption 0.70 (0.30 - 1.05)
1st calculation 10,900 divide by 1050Watt = 10.38 EER
2nd calculation 8500 divide by 700Watt =12.14 EER

so this is how i calculate.. i estimate the maximum and the recommended btu/h to see which 1 is the most high EER =)
thus power saving 

Yes, an important advice.

Mitsubishi Electric (Melco) is one of the brands for single split where 2.5HP is one size up than the rest. 3/8" (9.52mm) vs 1/4" (6.35mm) for liquid (returning to condenser) pipe.

The only other type is ceiling AC where crossing 2HP, have to beware like Melco that liquid pipe (returning to condenser) scenario: one size up.