Yes, you should add salt(aquarium salt, NOT table salt!), about 1/2 teaspoon should be good(remember to add 1/4 of that for quarter water changes). The temp. is fine, but be sure to keep the room your Betta's in the same temp. because you can't use a heater in a bowl. Bettas are pretty sensitive to water cleanliness, so you might want to remove the gravel because it's hard to keep clean. You got your Betta 10 days ago? If you set the tank up right before you got him, it has not finished cycling. Go to
www.fishlore.com/NitrogenCycle.htm to read about the
nitrogen cycle. Use the product Cycle to speed up the process and keep up the water changes. Also, I'd try Aquari-Sol instead of Maracyn--it described a parasite exactly like what you were describing on the package(I keep some because I'm getting Bettas, too). About his diet, pellets are pretty boring and may not have enough protien, so I recommend feeding freeze-dried bloodworms & freeze-dried
brine shrimp at least several times a week. And I highly recommend the site
www.bettatalk.com, which tells you
everything you need to know about keeping Bettas and is an awesome site.
Hope this helps!
P.S. Thanks for keeping your Betta in a nice big bowl instead of those tiny ones some people use--your Betta will appreciate it & live longer, too.