To answer some of your questions...
1) i cant find them anywhere but i hear they sell them a petsmart (but i've also heard places like petsmart and petco often have sickly fish)
Each shop seels what is "Hot" in there area. If it is a popular type then they will most likely have it, if not you will have to look alittle harder. Not all chainstores are bad. Look at the tanks, see if they have alot of dead fish and how clean the tanks are. This will give you an idea of how well they treat there fish and if you should buy from them.
2) what do i need to do to get this tank set up
As stated you will need a filter, lighting, gravel, live or fake plants and maybe a heater. Most times in a small 10g the lighting may be enough to keep the tank heated. Also the temp outside the tank will help keep it up. You will also need a freshwater test kit, water conditioner, food, gravel vac & thermomator.
3) ive been looking at various websites and there is some controversy on weather the dwarf puffers are brackish or freshwater
Freshwater is the way to go with these guys. They will need a lot of plants in the tank to keep them happy. Don't over do it but make sure to have a good amount. Also make sure to have a couple smaller caves for hiding as they will like them. These fish also like to nip at other fish so don't add any fish that have long fins or there will be trouble. They can also get pretty mean so I would not say to add any other type of fish with them. Puffers should be fed shelled food once a week to keep the growth of their teeth under control. Go with say 1 male and 2 female for the tank and see how that does for you.
On a side note make sure you have the tank fully cycled before adding any fish. Do a search on the forum and you will find alot of info regarding cycling a tank. Make sure you are ready to do weekly water changes of say 30%-40%.
I hope this helps alittle. Good luck and if you are unsure of anything just ask and someone will help you out.
