In the tart recipes in the first Jamie Oliver Naked Chef books, he gets you to slice bits off the pastry when it's hard and piece them together in the tart tin rather than roll it out - it's quite a nifty idea because it's easier if you're a beginner than doing the whole rolling pin thing (though once you're confident at all the rolling out that's quicker). It also means the pastry gets handled less so it ends up lighter. (No good for a pie though.)
I've always rubbed in using a food processor, not yet tried with the KMix. You can't do much in one go though (and the Prospero's fp bowl is quite dinky).
Rubbing in does take forever when you're doing a lot.
Re the quantity of water, this is the story of how I learnt to do pastry.
When I was a teenager my mum asked me to do the pastry for her mince pies. I forgot it needed water and made the pastry stick together through sheer determination and force of will. The mince pies crumbled in your hand but they were the most scrumptious thing ever. Several people told me they were the best pastry they had ever tasted. And all because I had got it wrong.
After that I realised that the less water you use, the better it is. So put in a little at a time (ice cold), just enough to make it stick together. If you put in too much the whole thing will still work absolutely fine, it just won't be quite so melt-in-the-mouth, but it will still be lovely because fresh home-made pastry simply is lovely. If you put in too little it will fall to pieces but that will be balanced out by the fact that it tastes better, so it's a trade-off.
The secret with pastry is never compare yourself to Delia or Mary Berry or the women in your local WI. If you do that you will lose confidence. Compare your pastry to a Taste the Difference fruit tart from Sainsburys and yours will actually be a hundred times better because of being all fresh with nothing but proper ingredients.