I'm on the opposite end of the buying/selling an eventer 'experience'. I have a lovely talented boy who has been ridden by a novice - my daughter - and has looked after her through all sorts of , shall I say, not quite professional-standard riding! His BE record reflects her, not him, but people...
Neue Schule 'Verbindend' or 'team up' depending on what stage their schooling is at - a snaffle with a central lozenge so it fits in the mouth neatly as they tend to have big tongues and narrow mouths. I'd recommend going on the neue schule website then ringing Heather there for advice.
I'm using Naf mud guard powder. Not used it before this year but several people on the yard swear by it. Various comments on the internet said some horses wouldn't eat it, but my picky mare doesn't seem to mind.
I've not tried to trace a number but have found their switchboard really helpful whenever I need anything - might be worth a phone call to the number on the website (they all speak English!)