Scale of garden - what size do I 'need'

I think your question's neigh on impossible to answer. For me it would be a minimum of a half acre. Others will say much more and much less. Have a look at gardens belonging to friend or neighbours to get a feel for what you want.

It depends a bit on where you are. If you are looking out the country you might as well look for a minimum of a half acre, though you do tend to spread yourself out if you have space. If you are looking for a house on an estate you won't get anything like a half acre, but in fact you could get all you mention into a reasonable urban garden, especially if you look for a bit older house, they tend to have a bit more garden.

Given the OP's view on the size of veggie patch being envisaged, I am not sure they are going to be into managing a 1/2 acre garden, that's 50x40m. Even a large urban garden requires a lot of effort and no little expense if it has a lot going on other than just an expanse of lawn. Great if you're sure you are into that but while I am keen to have an attractive garden with several features, there is a limit to how much time I can invest in it each year. When I was house hunting a few years ago, I was therefore looking carefully at the gardens on offer. I was more concerned with the aspect and current condition rather than the overall size once it wasn't miniscule (ie.e, couryard) or gigantic (>20m long).

I eventually ended up with a 10x7m south-west facing mature back garden which had a deck, shed, covered work area, some mature trees and climbers along the boundaries and a flower bed put in by the previous owners. I'm in the (extended!) process of replacing the small paving/lawn area in the middle with a single raised veggie bed, a wild flower bed and a 2x3m-ish pond/cascade. So you can fit a lot including everything in the OP's shopping list in to a small urban garden, it's just about layout and working with what is already there. If I did have more room, it would be given over to more vegetable growing - there is only so much you can produce in a single raised bed

I think having a veg garden at the front depends somewhat on the style of your house. If it is a very conventional, formal arrangement then you really have to continue the theme and have the front as decorative. If its older or more traditional looking, and depending on the general look of the place, you could put your veg out front. If you decide to sell you might have to reorganise it to make it more conventional looking, most people really don't like unconventional.

Agree about house in the corner of the site, it gives you a much bigger sweep of garden, and I think looks more interesting than the 'stuck in the middle of the plot' houses. Though even then the shape of the drive and tree planting can settle it into the landscape.