To answer your questions:
The Cult's respected as a force among the rest of the Horde (talking about guilds, of course). They don't trust us or particularly like us, but have a grudging respect towards our skills, which is why we're invited to take part in various campaigns. The Cult returns the attitude: We despise all of the living equally though we preach that the Horde is an ally in need and such should be treated with respect. Nevertheless, it usually shows we don't think much of them, much to the chargrin of our more politically minded brethren.
To put it short, we tolerate eachother and respect eachothers skills, even if grudgingly.
Of course, it is not that simple - we have somewhat more friendly relations with the Blood elves because of our close borders and various pacts, also we've found some similar souls (even when we don't admit it) among the Sunfury Elite. We've also gained ties to the Second Gurubashi Empire that keeps itself away from the Horde, even though it at times works closely with it.
This is the IC version of how things stand.
OOCly we, naturally, try to keep close relations to other RP guilds and are good pals with everyone!