I'm having second thoughts about renting out a room to a friend, does anyone have any advice?

A friend of mine who I've known for quite a long time was in a bind, his landlord sold the home he was living in and in his current situation he could not afford another place on his own and couldn't find any one else to room with, etc. So he asked if I would be willing to rent out a room in my house to him, so after a lot of back and forth I relented and said he could stay..now I'm freaking out with about 2 weeks till' he moves in I'm finding that I offered to sacrifice a lot of space and privacy that I'm really going to be missing once hes all settled in. I'm also, well I've been for a while noticing a decline in how friendly we are to one another, when we first became friends we were inseparable - even best friends at one time, lately (like in the past year or two) our contact has been more and more sparse and I just feel a strange distance from him. I tried having one of those 'rules' talks (house rules) with him and that didn't go well.. we disagreed about how we should split the food, he seems to think that when two people are living together they should just buy enough food to share with the other person who lives with them - in fact his exact words were "usually whenever I go grocery shopping I just get enough of whatever I'm buying for the other person too".. I've never had a roommate, but I have never heard that EVER. I do not plan on buying more of whatever it is I buy for myself usually because he may want some too.. I don't like that I'd prefer we each bought our own groceries, we also didn't agree on how late he should be able to have guests (this is MY house mind you), I'm worried that he'll bring friends of his over who I don't like and who don't like me (I'm thinking of one mutual ex friend of mine in particular) and who I won't feel comfortable having in my house near my personal effects - is it ok to ask somebody not to bring someone around when they are sharing the space and living there too? I'm worried that he'll smoke my weed without asking, eat my food, that our cats won't get along (and that mine might feel intimidated in their own home by the presence of his cat - I told him he would need to keep his cat in his bedroom for a month or so till the cats got used to each others scents and he was very opposed to the idea of keeping his cat confined to one space), I'm wondering how we're gonna get along after he moves in(will our friendship improve or is that naive? is it bound to continue on this decline?) after years of knowing him and previous trials to our friendship and I'm worried that the end result of this will be the final push that ends our friendship. I'm just really feeling like this is a bad idea but I'm having a hard time reaching out to him and telling him all this. After 10+ yrs of friendship we've kinda hit a snag in our relationship and are no where near as close has we used to be (we barely talk, we haven't hung out in the same social setting in months,when we do hang out it seems almost awkward and detached you can almost say 'forced' in some ways), I would prefer to continue to live alone but if I'm gonna take in a roommate I'd much rather it be one on the upswing of our friendship not this weird strained friendship like the one with my current friend has become. I don't want him moving in and I feel like he only reached out in desperation and that hes moving in somewhat under pressure and due to stress and with no other options - so hes kinda settling to live here because of his limited options which eventually I think will breed resentment... so I'm pretty stressed out, I'm thinking this is gonna turn into a disaster and I also feel that now after the "talk" hes dodging me (we went from talking pretty regularly after he first asked to move in to maybe once every couple weeks in the past few months or so, I haven't heard from him well over two weeks now, which is also the amount of time until hes due to move in) till its time to move in so that I won't get on his case but also partly because we're not even that close anymore, it just feels weird.. sigh..any one got any words of advice?