Help with extending a concrete patio, please

[kia cat]

I'm hoping the link above shows our patio at the moment. The aim is to extend out following the red outline. On the longest lengths it's just over 3 metres. The fall of the existing patio is towards the X. My questions are:
[1] How do I calculate how much concrete and what mix would be best. [I'm assuming we should be aiming for about 50mm of concrete depth, on top of some compacted hardcore?]
[2] Can I get the fall from the new patio to come towards the existing.
[3] Would I need an expansion joint between the old and new? Thanks Builder & co! Media URL: http://img705.imageshack.us/slideshow/webplayer.php?id=gardenpatio1.jpg
Description:

[boxtops]

here's the link http://www.theanswerb.../Question1026965.html

[The Builder]

Ok KIa........ this could get complicated, so I'll try and keep it simple.
1 It's an odd shape, so measure the average length by the average breadth. If one side varies from 1 metre to 3 metres, then the average is 2m (approx!)
Multiply the result by 0.05 (50mm thickness of conc.)
1 cubic metre of conc weighs roughly 2 tonnes. Just looking at your pics, I guess you'll need something like 0.2 cubic metres (200kg).......... (very approx)
Scratch off the turf and any topsoil, and replace with hardcore. The Pros tend to bed on compacted sand only........... some use "dabs" of sand & cement as well. Everyone has their own way. They do it easily, but you could have problems with sinking etc if you're not used to it............. so bedding directly onto concrete would be a good one for you

[The Builder]

2 If you fall towards the existing, you'll need to create a "secret gutter" to take away the water................ or it'll undermine the support for the slabs eventually. Again,this is just one way to do it. Your problem is that the present slabs might be level ....... so water won't run to the side and away from the patio.
You could dig a little way under the existing and bed a length of plastic gutter under them.............. so that the existing slabs and the new ones overhang into the gutter. Bed the gutter to fall ......... somewhere!. Keep old slabs and new slabs maybe 10 or 15 mm apart so that you can poke something in there occasionally to clear the inevitable bung-ups.

[The Builder]

3 Even if everything is grouted tight........... it's not a big enough area to need an expansion joint. If you decide to go with my previous post, there'll be a gap anyway. :o)

[AlBags]

If you need to, peg the area out with some wooden pegs and a couple of straight edges (timbers)