alright everyone it's only the ninth post... and she is getting better (no sea horses).
Samantha I'm linking a page with info on the Porky Puffer
here.
Please read it over, the minimum size tank for a puffer that it recommends is a 90, though you maybe able to house him in a 75 while a juvenile, he will still outgrow that too. As far as compatibility wiht the other fish goes, yes it can be compatible in a much, much larger tank, where it wont have to fight for territory.
Now your selection of inverst is fine. Though you still have a lot of fish in your list, I still reccomend that you narrow it down to at least 2-4 fish depending on size of the little beasties.
The damsels...are recommended for at least a 30 gallon to house, though you could hold them in yours also. However as they age they get very, very mean! very protective of there section of their tank...they will fight with everything else in your tank as they age. Damsel also get a pretty good size up to 6" and when they get that big, whoa! lot of attitude!
Narrow it down a bit, and you may have a working combo, if you go with damsels after all, i would do nothing but 2 maybe 3 damsels in that tank.