Definitely not a fremontodendron. Looks more similar to a camellia leaf. A picture of the actual shrub would help a lot.
Looks like an ash tree
I use an empty compost bag turned inside out - they are black on the inside. Most of the big bags reach the length of my troughs. I fold them around at the ends to get a good fit . I usually make some holes about an inch up the sides to allow water to be retained at the bottom. You don't see the black for long as the plants soon cover it.
Looks like Claridge Druce to me but as Nutcutlet says here are so many different variations it is hard to be sure.
I wonder if it is one of the Sorbus family...looks like my whitebeam but I think the leaves are not quite the same...
Use it all the time - great stuff! The only reason that I know that could cause a problem is applying it neat or not dilute enough which could burn the roots and cause harm. However you have the dilution rate spot on and I see no reason why it should only do good to your plants.
What sort of berries does it produce?
Could you post a picture, it will be easier to id
The marks on your pear tree are unconnected in my opinion. These marks are pear rust.
If you want to find out more about hedgehogs I can recommend a great book I am reading at the moment which dispells a lot of myths and explains alot too.
The New Hedgehog Book by Pat Morris