Grafting

I bought and planted an apricot tree in my garden, which later on I found out was an almond tree with an apricot branch grafted onto it. Does this constitute kila’im? If so, what should I do with the tree?

Is it permissible to plant a tree from a lemon tree scion grafted onto a hushhash (sour orange) rootstock? Is there a comprehensive list of all the permissible grafting combinations? Are there any nurseries that follow halacha?

If I bought sapling for my garden at home, when I bought them from a person who I don’t know (he looks like he is religious; he was wearing a kipa), is there a problem for me to plant them in my garden? Please note that there are five different trees: 1) lemon, 2) orange, 3) tangerine, 4) pomelo, 5) guava.

I live in the Diaspora. I have three mature Burr Oaks growing in the front of my property which give a lot of burr acorns. They are edible, though we do not eat them. My property is too small to add pecan trees in it, and I do not wish to destroy good trees. Is there a halachic way to graft some pecan branches onto the burr oaks in order to yield pecan nuts?

Can one say birkat ha’ilanot on trees grafted in a forbidden fashion?

Is it permissible to graft several types of citrus fruit (tangerine, lemon, orange, etc.) onto one tree?

I grow different types of berries. Can I graft a blueberry onto a strawberry tree (they are from the same family).

Can I say birkat ha’ilanot on a tree with several types of fruit growing on it?