Well, if you are going to any tack shop, ask the owner. A basic horse, needs a medium to large halter. small ponies can use foal/yearling halters. if you have a Draft(large breed) then they need the biggest one you can find.
A headcollar
If you have a calm horse put the reins over it's neck, remove the headcollar and quickly puton the bridle, do not do this with a horse that will spook easily or is not well behaved, perhaps tack up in a stable.
you undo the buckle closest to the back-end of the horse... or both if thats easier
The difference between a headcollar and a halter is that a headcollare is attached at the neck.... giving tho horse a free head. It has the same use as a halter , just giving the horse more comfort
a horse wears a bridle whilst ridden or a headcollar or halter when in or being led from or to the field
A headcollar (non-nylon), a leadrope and a rug if it's raining/very cold/if your horse is thin-skinned. Remeber to take off both the headcollar and leadrope so the hore does ot trip on it!
depends on what type pf harness you mean. For tying them up say in a stable or horsebox, we use a headcollar, for riding them we use a bridle. but there are many different types of headcollar or bridle.
it a bit like a bridel but without the bit.you use it to lead the horse from the field and to tie it up when you want to groom it.
when riding-get a stronger bit or martingale(or have lessons to gain control) when leading or around your horse-get a headcollar with a bit so you have more control when leading!
A Large size
a cob is a pony with horse proportions generally. so yes, the headcollar would be slightly larger
This will vary from horse to horse. To determine blanket size measure from the center of the horses chest to the center of it's tail and that should be the blanket size, if it is a odd number go up one size.