i've been with my boyfriend for almost a year. He doesn't talk to me much about how he feels about me but if i ask him a question then he'll answer it

Not very many men, will talk to women about how they feel.  It is just not what most men do.  Yes he will answer the question if asked, but then he will probably say what you want to hear, whether truthful or not.  But men in general don't talk about their feelings that much, so it takes a woman to actually raise the subject.

so i know he likes me alot, likes having sex with me and thinks i look good. i've ask him about things he'd like to be done to him or like to do and most of them i've done (still got the threesome to do but that will be for his birthday).

From what I've heard, very few women like the idea of a threesome.

i'll do almost anything for this man so why is it that he looking for sex elsewhere, dating agencies, escort services, swinging clubs etc on the internet.

I don't think that is normal behaviour for a man that finds a woman attractive.  Yes most men will want to experiment with sex and will want sex with other women, but most men will not carry it out unless they don't value the relationship they are in.  You would expect a man to be looking a porn and maybe even swinging clubs on the internet.  But to be looking at dating agencies and escort agencies, that would really worry me.  The swinging club thing, would involve you going with him, but dating agencies and escort services would not, so that's why they would worry me.

i really don't understand how a man who has a woman that is always hungry for sex in different places and ways and wants to please and tease and take to so may height of delight and dirtiness would want to look elsewhere.

Most men have a very good appetite for sex.  But there are some men that have an unhealthy appetite for sex.  They want to be doing it all the time and experimenting all the time.  I think that type of man you need to be very wary about, he sounds like a nymphomaniac that is never going to be satisfied until he pushes the boundaries even further. 

He doesn't sound bothered about who he pushes the boundaries with.  If he is looking for other people, then it is more than likely at some point he is going to be unfaithful with you, he will also be pushing you do things you don't want to do, he may not be now but eventually he will be wanting to push the barriers even further. 

I think it is time you started to look for a different man.  Unless you feel comfortable about having sex with other people and feel comfortable about him having sex with other people, because it looks like he is moving towards that goal.  And more than likely will take his sexual antics further in the future.  It is all about whether you are comfortable about experimenting with sex, some women have just as much appetite for experimenting as men, but I would say they are a minority.  Some women like experimenting but not to the extent that men do.  By the sounds of it, you like experimenting but not to the extent that he is looking at.