The last one is not poison ivy or ivy. It appears to be a bramble (Rubus spp.) which includes dewberries and blackberries. I am fairly sure I can see the prickers on the stem.

Thank you.

2 and 3 are mainly Morning Glories. 1 is Asparagus densiflorus 'Meyersii' aka Foxtail Fern. But it is not a fern. 4 is indeed a Rubus.

Thank you. I was just out there and stepped on a snake. I'm guessing they like the area because of the berries? Yuk!

All the snakes I am familiar with eat creatures ranging in size from worms and bugs to small mammals. They are probably enjoying the garden for its mix of sun and shade so they can regulate their temperature - being in the sun warms them if they are too cool, and moving into shade allows them to cool off when they are too hot.