I'm no expert but I think any minimum you run into would be is if it was too close to the house. Such as "it has to be x-amount of feet away".. Septic tanks require a leech field surrounding them wich take some area too.
I would think that as long as there is a decent fall(angle)for the pipe from house to tank you could locate it almost anywhere beyond local code's minimum distance. If it fits with your site plans I would locate the home on the highest ground that is convenient,that way everything can flow to the tank easier/faster. But there again,I'm no expert.
For tank systems environmentally friendly soap/shampoo/laundry soap/cleaning solutions etc are better for your well water's quality. Any liquid you put into the ground finds it's way down to the aquafer,sadly they are more expensive than chemical soaps. The leech field handles liquid overflows,pumping out the tank is primarily the solids.
this link has some DOs and DON'Ts- http://images.google.com/imgres?imgurl= ... s%3Disch:1
Wow,long link,,hope it works.