The general campsite is on a hill, but there are flattish patches to be found, especially near the top of the slope where it evens out quite a lot, and on the extreme edges of the site - the worst of the gradient is up the centre path, I think.
I've no experience of tipis myself, but I've seen them at BDays and I'm pretty certain they stayed upright for the duration!
We have arrived bang on 9am for the past two years and found the favourite pitching areas already claimed by the ubiquitous 'tent villages' - you know the ones? A handful of people with the glint of a property developer in their eye, a dozen unerected tents spread out on the ground, windbreaks, gazebos, taped off gardens etc etc.
There will still be a reasonable amount of space by lunchtime, but you'll have missed out on anything the 'right distance' from taps, toilets and tea, or close to a fence, tree or pathway, I would imagine.
I don't think the tent spacing is anything like as dire as Glasto's Big Ground (thank God!) and there's usually been more space down towards the Bimble Inn area (bottom right as you enter the field) rather than the top end of the site where the best view of the main stage is.
Apart from in the arenas, the majority of taps and toilets are around the perimeter of the camping field, though that isn't quite as scary as it sounds because the field is sort of oval shaped and you're never really more than staggering distance from them.
There's only been one shower block in the general camping are in previous years - usually on the far right hand side near the top of the hill as you walk up the main paths.
Obviously, all this is based on earlier layouts and may change this year so don't take my word for it!
Have a great time and I'll look out for the tipi.