Why should i buy from amazon when there is a disclaimer stating not to because the kit could be rejected?

What the others above said was correct. It’s sold by Ancestry but shipped by Amazon. (Like most things here. Brands/sellers are selling their item on Amazon & Amazon ships. I just got my results back & my adult son should have his back any day. Super easy process and it’s fun! I was very surprised by mine. 100% Trusted to buy from Amazon. If you buy it from Ancestry site you’ll be paying like $40 in shipping (I think it’s actually more than $40) & why I purchased them here! Good luck!

Does this kit provide info about genetic snp's like mthfr mutations?

The AncestryDNA or 23 and Me “Ethnicity + HEALTH” tests DO provide info as to what gene mutations you have and a list of what health issues you are dispositioned for due to said mutation. I, for instance, found out I have the MTHFR gene mutation. I learned who I got it from & some scary stuff, such as, being dispositioned for Schizophrenia and miscarriages (and about 99 more things). It is really hard to find a doctor who knows anything about it. You’d need to visit mthfr(dot)net and research for yourself. Sadly.

What happens to your DNA once the test is performed?

I've been a member of 23 and Me for years now, and have relatives I've never met as members. It has been more than helpful when a cousin of mine in Pa (I'm in SoCal) was working on a large genealogy project. My findings have been nothing short of fascinating. I've been participating in their research, for which I gave them permission to use my DNA. There are a lot of autoimmune diseases that run in the family, and it's been extremely helpful to know the gene mutations. I haven't been the "victim" of any kind of nefarious activities because of my DNA being submitted.

It says you need an Ancestry account. Do you have to pay for their online site?

No, you don't have to pay, yet again, to see your results. If you want to see how you relate to other people via your DNA, yes, you do need a subscription. There is a 50% discount for the first 6 months or so, but you need to ask for it. I found my Father using Ancestry, BTW.