For distance, a lot depends on the variety. Some are MUCH larger plants than others. For the most robust variety I grow, I generally plant a couple of seeds to a "hill," and thin to two. I place my hills about 6-8' apart for this variety. For a more restrained variety I might place hills as close together as 4'. Planting in a row works well too. I haven't done this with the most robust kinds. But say, for an acorn squash, I might do a row, leaving 6-8 feet empty space, to either side, and plant my seed one per foot, within the row.

A general rule to remember is that, at planting time, one almost always thinks that a plant will take up less space than it actually will. So, be extra generous with spacing. You'll be glad later in the season.

Unless you live in a cold, wet environment, a "hill" probably doesn't need to be raised. In a really hot, often dry climate I've made my "hills" concave, in order to catch and hold water. "Hill" simply refers to the planting pattern, not to the altitude.

When I plant I often put a couple of scoops of rabbit or goat manure under a hill, or dig in some of the same along my row. The absolute ideal, in my mind, would be to dig a large hole (wheel barrow size), fill it with manure and pile it a foot or so high, above the hole. I'd do this right after garden clean up in the fall, letting it rot all winter. Then, I'd plant a "hill" of squash or watermelon there. Every have a squash come up in a compost pile? They grow very very well.

Once planted, I usually don't fertilize. But it wouldn't hurt to side dress with some sheep, goat or rabbit manure. Coffee grounds could be used as a side dressing with no danger of burning the plants. I'd absolutely avoid uncomposted chicken manure. It's too strong. My preference is to do the soil building months before planting, plant and let things grow without further treatment. Long term soil improvement will usually win out over topical application of fertilizer. Even if you dug a hole and dropped peelings and other organic kitchen scraps in there, during the winter, I bet you could plant a pumpkin in there and have very good results.

Many gardeners over water. If the plants look fresh and alive, chances are you don't need to water. If in doubt, dig down (not right next to the plant) several inches into the soil. If it is damp, say at 3", you're probably okay without watering. When you do water try to water deeply. If watering a "hill" of squash you could set a hose, dribbling, right at the base of the plants, for a couple of hours. If using a sprinkler, try to water for an hour and a half to two hours. You want that water to sink down deep, and you want the squash's roots to go down after it, increasing drought tolerance. So, when you water, water deeply. Then, don't water again until things are truly getting dry. When the moisture starts drying out of the soil you want those roots to go after it, digging in deeply and increasing drought tolerance and the plant's ability to feed itself.

Watering is best done in the morning, if possible, so that any water on the leaves dries quickly. Letting water linger on squash leaves can lead to powdery mildew.

Where are you gardening? What is your climate? Here in Oklahoma it is very true that one shouldn't water while the sun is high. The water on leaves can serve to augment the sun's strength, causing the leaves to burn.

The only real disadvantage of mixing varieties of pumpkin might be that some are much more vigorous than others and might crowd them out. Below is a link to a thread dealing with different kinds (use of, and species) of squash. It might give you more back ground on all that's out there and what might do best in your climate.

George
Tahlequah, OK

Here is a link that might be useful: Green Country Seed Savers Link on Kinds of Squash