I have studied self sufficiency for many many years now, and i am slowly
making my way to becoming such. it's so much more than land, or climate or
anything like that

it's a lifestyle change, a soul change and mind change...

some of the number 1 blunders in people "getting back to the basics" are
caused by dreams and a lack of thought...

if your alone its dead easy, you eat as hard as you work...if you have a
family to support it's very different...

as for how much land? thats another story, dependant upon your climate you
need to plan for winter months, and what to eat then....what about heat?
water? all the things you talk of (off grid, rainwater, etc) those require
money and space to supplement what you're cutting yourself off from.

what if it doesn't rain for weeks? you have dead crops, animals and your
drinking ditch water boiled for 10 minutes filterd through a 15 year old
tshirt...

it's the most fullfilling thing on earth to sit down to a meal that your
sore muscles, bruised bones and bloodied fingers prepared....sitting by a
wood stove with wood in it your grew and cut...drinking water from a spring
that comes to your house by gravity -- that you dug....sitting on the porch
drinking beer/wine that you grew/malted/fermented yourself....

to answer your questions would take alot more detail from you, you have an
awesome dream...there are alot of good resources available to help get you
started (there is a great book i have read about that lifestyle, he makes
all the mistakes so you don't have to) there are several other books to get
that help you develop basic skills (such as, if your tools break or if your
tractor breaks, how to do you fix it? welding/blacksmithing/etc) subscribe
to some magazines, get in touch with locals (or non-locals) that are doing
the same thing, get your dream on paper, get it out so you can look at
it...ask yourself a million questions NOW, so you don't have to beat
yourself up over them when you didn't think of something later...

enjoy the quest, it's worth everything you put into it.