How to read cladograms/phylograms?
-Bacteria 1 is least related to Eukaryote 4 (the furthest branch is always the least related as there common node is furthest away, correct?)


In terms of relative relationships, eukaryote 4's least-related relative is Bacteria 1. Bacteria 1's least-related relative is the entire rest of the tree


  -The most related organisms are Bacteria 2 and 3, and Eukaryote 2 and 3


You cannot actually answer this question because a cladogram only shows relative relationships. To know which species pair is the most related (has the least total distance between them), you would need to know the branch lengths.


  -Is Eukaryote 2 the least related to Bacteria 1 as its branch is the furthest away? 


To determine relationships, you want to look at the total branch length between two species. Therefore, this is correct


  Or is it Eukaryote 4 as it is the furthest away (bottom of list)?


Avoid this way of thinking. A phylogeny is not a 'list'. Pay no attention to the order the species labels appear: you only want to pay attention to how the species are connected. The same phylogenetic tree could be drawn differently, placing Eukaryote 3 at the bottom, for example.


  -Is Eukaryote 1 most closely related to Eukaryote 3?


Eukaryote 1's closest relative is Eukaryote 4: the distance from Eukaryote 1 to Eukaryote 4 is the shortest out of all possible pairs with Eukaryote 1.