First off I'm not a gardener.

Were your existing large bins filled as batch or continuous? If batch, I am going to expect a 50-60% reduction in volume by the time it's finished. If continuous, not so much reduction as some has already taken place.

Is your garden for vegetables? I've heard that veggies are more demanding of nutrients and stuff. Do you till a lot?

As it is your bins have a volume of 16 CY or so if filled. Shrinkage could take that down to as low as 8 CY or so but more likely into the 12 CY range.

To cover a garden of your size with 1 inch of finished compost you would need just over 13 CY of finished compost.
One inch doesn't sound like a lot but it should be sufficient if the compost has decent numbers and the garden soil wasn't dead to begin with. And with 5 of 7 years having compost added I would suspect your garden is in pretty decent shape. I don't think even 2 inches would cause any harm but it might be more than you require.

Your compost ingredients sound fine to me with the caveat that the HM came from healthy animals.

Lloyd

How much total organic matter you can add to your soil depends on what that soil is like. What you want to have is between 5 and 10 percent organic matter in your soil, and just how to get that depends on many things starting with how active is your Soil Food Web.
To put things in perspective, a bit, Keith Baldwin (a soil scientist at North Carolina State University) suggested in an article he wrote for Taunten Press' "Kitchen Garden" magazine some years back that you needed to till in 8 inches of peat moss when starting with a clay soil with no OM in it. That is a lot of peat moss and of course we know today there ae better, renewable resources that can be used instead.

I put lots in I don't think you can possibly have to much if its composted Oh yeah and I usually ignore my parents also (:

Fespo, how does your garden grow? ;-) Since manure is high in nitrogen if you add too much you will have fast green growth (as Dad says) but perhaps not good formation of fruit/veggies.

If you are happy with your crops then keep doing what you are doing.

If the manure is sufficiently composted, as the OP states, it will not contain excess nitrogen. The NPK of composted horse manure is only .70-.30-.60. Its primary value is that of providing organic matter, not of being a high nutrient source.

I grow giant vegetables like 1000 pound pumpkins,50 pound cantaloupe and so forth. They require lots of nutrients.I add about 30 percent composted horse manure every year,and about 20 percent peatmoss and a little lime.My veggies do great with all that compost.So I don't think you should have any problems.

According to all of the charts that I have seen what gardengal has posted is the NPK of fresh manure. The nutrients in properly composted animal manures will not be available enough to test, just as the nutrients in compost are not readily available enough to test, accurately.