2 storey renovation floor design help needed.

I have posted in go to whoa my renos so far and a little stuck on which way to go. I have endless options firstly I need to sort out the stair design (see my other post in stairs)
http://www.renovateforum.com/f199/ma...-stairs-93414/
Then I can complete the design of the house (is this called the dog wagging the tail?) design the stairs first before how the house will function. Note the "step" in the upper wall, which gives the change in direction of floorboards, hence why the stairs are going where they are. There is a door to the side deck but this can be moved if necessary.
The kitchen is staying in its little corner not a priority at the moment.

Should I replace the 240x45 F7 joists with 240 x 63 or 90 hyjoist (just checked cant use 45) ? I can reuse the F7 for the new deck (later off the rear) It also allows me to lower the floor by 19mm and put down T+G (improve insulation/sound). Either way the decking boards have to come up for the new floorboards (150x22 baltic pine to match 130x22 baltic 90 deg to each other).
I can also move the floor only current bearer higher (improve head room and noticeability in rumpus) joist are sitting on the brickwork (later to be removed) and I would then use joist hangers for the joists is this a good or bad move? currently the joist are sitting ontop of the bearer, this rumpus room would only have the one beam showing.
I improve the beam height by 240mm stick out (140mm instead of 400mm) the ceiling height is 2400mm is it worth the effort? Do you get a better result using joist hangers over ontop? where it is at the moment I also can underpin the post with a footing as the current strip footing looks like 200mm thick only (thats the way they built em back after the war).

Attached Thumbnails http://www.renovateforum.com/attachm...d-p6280243.jpg
Attached Files http://www.renovateforum.com/images/attach/pdf.gif floor plan lower storey-A3.pdf (25.5 KB) http://www.renovateforum.com/images/attach/pdf.gif floor plan upper storey-A3.pdf (36.5 KB)


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