First time cider brewing

Ok, ive decided to brew my homeade cider, and i beleive i have everythign i need, bar a few apples, but would just like some tips, and advice on my current understanding f what i need to do.

I have campden tablets and champagne yeast, as i dont want to risk using teh natural yeast off my apples. I have a 6-7 gallon plastic fermentation barrel, and also 7 demijons. I have stuff to sterelise them, a siphon, and a cider press and all materials for it.

Thsi is teh mix of apples im plannign to use, nto sure on the quatabties yet but here goes.

I will be using, discovery, worceseter, russet and cox. Also i have alot of greenish red apples from trees near me, that arent ripe yet but im not sure what they are.
Do i need any otehr apples such as crab apples, to get the taste right?
I understand they add the much needed tannin to the cider.

Also, how do i test the acidity of my juice?

Now with fermentation, i plan to add campen tablets to the freshhly squeezed juice, then champagne or some equivilent yeast, and let it ferment for around a week in a warm room in the barrel. I will then siphon into demijons with airlocks to ferment for a further 2-3 montsh till fermantation stops. Is ithis right? Also, if i have two fermentaion barrels, one with an airlock, can i instead of splitting the 7 gallons into 7 demijons to ferment, put it in the new barrel to ferment? Or is this not possible.

Also i woudl liek carbonated cider, and i hear if you add caster sugar to re-start fermentation when you rack it. Im confussed as to, when i rack my cider, which will probably be back into a barrel rather than bottles, if i add sugar to carbonate it, do i put an arlock on it, or just seal it?

Any help i can get to clear up this confussion would be greatly appreciated, as i think ive got most of it planned out correctly.

Dude, how many drinks did you have before typing this up (typo much?)

Anyways.... You are correct to add campden to the juice, just follow the instructions on the bottle for the amounts. Champagne yeast will work fine. I personally use Premier Cuvee, but that's just preference. This may help you out in deciding what yeast to use. Dry Yeast :: Midwest Supplies Homebrewing and Winemaking Supplies

When you carbonate, you want to seal the container you are using, which will force the CO2 bubbles into the cider. If it is not completely air tight it won't carbonate.

Yea, sorry my typing is appaling i really need to read what ive typed and take out my hundreds of typos!

Thanks, that was pretty much what i was wondering, all i need to do now is try and get a good blend of apples.
Will i somewhat be able to judge the sweetness acidity from the freshly squeezed juice?

Evening,

I wouldn't get too hung up about testing for pH and all that unless you were a commercial cider maker needing consistency and an indentical fermentation each time. A friend used to use whatever he could get from his couple of apple trees and donations of surplus apples from neighbours, got the juice out and fermented it. Tasted amazing after a few months maturing. It was random blends of apples each year and each year it tasted different, but still very good.