After a fantastic response to my request for questions and comments yesterday I thought I would start with the easiest one to answer - which is what I feed.
Of course by far the biggest component of the horses' diet is forage - either the grass in our fields or the haylage we make every summer (for those who aren't used to the idea of haylage, an explanation of what it is and how it differs from hay is here: http://rockleyfarm.blogspot.co.uk/2011/11/all-about-hay-and-haylage.html).
During spring and summer the horses are turned out overnight and are on the tracks, with ad lib haylage, during the day; during the winter they spend more time on the tracks and therefore more of their diet is haylage though they get some grazing as well.
I like them always to have ad lib forage - it keeps them all settled and even horses who normally bolt down their hay-nets tend to slow down and relax once they realise there will always be forage available.
We use 5 or 6 different feeders and as well as having enough to ensure each horse can eat peacefully, its also important to give some thought to where they are located. For instance, when there is a strong east wind the horses won't use the feeders on the eastern side of the tracks so the other feeders need to be replenished more frequently.
We are fortunate to have relatively "safe" grass as its organic permanent pasture with a good range of different types of grasses and plants. Most horses can cope with turnout here, as long as its not when sugar levels are at their highest (hence the restrictions on their grazing in spring and summer), but do always be suspicious of your grass if you have a footy horse - its easily the number 1 cause of sole sensitivity in my experience.
(PS: They aren't footsore, just sleeping...honestly!)
The next most important element of their diet is minerals. Of course much of what they need is already found in their forage but all the horses here - even good doers who need no additional calories or protein - are at least given a daily a mineral supplement containing additional salt, magnesium, copper, zinc and selenium - plus micronised linseed and brewers' yeast to make things more palatable. If they need no additional hard feed, they just have this in a small feed of unmollassed sugar beet.
These minerals are commonly lacking in UK forage at the levels needed for optimum horse and hoof health and so in most areas its important to add them. Here, we know what our forage is low in and can balance to that but if you don't know or source forage from different places its still worth feeding extra.
Most commercial supplements aren't high enough in these minerals but Progressive Earth are a great company who sell 2 supplements which both do the job - Pro Hoof and Pro Balance. You can find their products here as well as the link to their Ebay shop: https://www.facebook.com/progressive.earth - plus their customer service is second to none so I can't recommend them highly enough!
Once forage and minerals are sorted, that is often all that is needed for horses in light work or who are good doers. For the horses in hard work or who need additional calories and protein - perhaps because they are lacking in muscle following a period out of work - I add alfalfa pellets, crushed oats and Coolstance copra meal.
The alfalfa pellets (which are available from Dengie) are infinitely preferable to alfalfa chop as they are much less likely to make horses footy. Even so, in areas where forage is high in calcium it may be safer to avoid them. They are a good source of protein but are high in iron and calcium so use with care.
Crushed oats are a good source of additional energy - contrary to the old wives' tales, they don't blow horses' minds, at least not that I've ever seen here. Cereals generally are something to avoid but oats are the highest in fibre and lowest in starch and so are a better bet than barley, wheat or maize. They are also readily available, cost effective and horses love them!
Coolstance is a good, though expensive, feed for really hard-working horses. Its high in protein, has a very good range of amino acids compared to most horse feeds and is also low in starch. Its relatively high in oil and provides slow-release energy which is ideal for our horses when they are hunting.
Hope that's useful, and now I'll start working my way through the rest of the questions!