My poor sick Betta :(

Question
Hi Bethany!
Well I am on a mission to save my very first Betta fish from despair after watching him suffer poorly for the past 5 weeks at our work office!
No one seems to care for him so I am taking it upon myself to help him [and the one little Platey [sp?] left]
He [Alfie] has next to NO tail fin left and he stays close to the top of the 10 gallon tank nowadays keeping his other remaining fins close to his body, rarely eating and seems generally miserable.
I treated him with some powder from Petco for FinRot for 6 days straight. I bought him and his buddy a 26 gallon bow tank with all the set up [ie whisper filter size 30, heater and thermometer] and have it all up and running today.
I shall run it for a week before I attempt to add them to it. I bought all the water testing kits and water treatment stuff to add to my tank water.
As I am new to this I am just asking for general info on what I am to expect when I add them to the new tank. Should I use some of his current water along with the water I have running in this 26 gallon tank?
How much water should I use to transfer to the new tank? 25%  or less?? My home tap water is rather high in ammonia so I know  i must get rid of that before I add them. Will the filter do this automatically over the course of the week i have it running? OR do I add something to the water to dissolve first??
How do I transfer the fish once I am ready 7 days from now? Arghhhhhhhhh  so much to learn I am afraid  of them dying on me as I have grown to love them both a lot!!
I intend on adding more fish once these guys survive the whole experience.
Thanx for your time. If anyone has any good tips Id be most happy to read them and very very greatful.
Gina  [and on behalf of Alfie and Petey!!]

Answer
Gina,

I would hug you if I could. Buying a tank of this size for both of those fish have made their life spans together a whole lot longer. However, for adding more fish: Betta Fish are VERY aggressive and territorial. Suddenly adding new fish to the mix can cause bullying (from him) and possibly killing or fin splitting. However, some fish do go well with Betta. For proper Betta tank mates, I suggest getting something dull in color (such as a Cory Catfish) and something that does not have long fins (such as Fancy Guppies - those are a no-no). Just be careful, once you add the new tank mates to watch very very closely for bullying from your Betta.

YES. You should use some water from the current tank. This will help quicken the process of necessary bacteria for the fish in the new tank. I would say around 10-15%. If your tap water is high in ammonia, you may want to do some constant ammonia testing. I believe their are some products out in the market today to help lower the amount, but the filter will help and you can do 25% water changes once a day until it begins to lower.

Now, as for transferring the fish into the new tank: "NEVER EVER EVER use your hands to transfer Betta or any other fish. Whatever chemical you may have on your hands can kill the fish immediately (including soap or anti-bacterial) and the oil from your fingers can clog fins (not to mention all those germs that our immune system is well prepared against!). Besides, Betta tend to bite. (I learned that with my first Betta while I was feeding him.)
Also, never just dump fish in the water. The sudden pressure of all the water can burst their swim bladder - which will completely destroy their swimming ability.
In other words: Use a net. ^.^

For food: I HIGHLY recommend some freeze dried blood worms or Brine Shrimp for your little Betta buddy. They love them! I give my Betta 4-5 Blood worms twice a day and he's happy as a clam!

Maintain the temperature of the tank between 72-76 degrees. This will cause an incredible difference in your fish.

Anymore questions and I will be glad to help you!