Hi,
I have a 5.5 gallon tank with one betta. I used Bio-Spira too. When I added it, I poured it on my sponge filter, then put my betta right in. After 24 hours, your tank will be cycled (0 ammonia, 0 nitrites, and 20-40ppm nitrates). It's a good idea to test your paramters just to make sure that everything's ok. I saw a small ammonia spike between 0 and .25, but it cleared up by itself the next day.
Yes, add the Bio-Spira cold. Don't let it warm up. I know, I wondered the same thing -- it's cold, and you're putting it in a warm tank! But apparently it works fine! You're not adding enough to change the temperature of your tank, so don't worry about that. If you don't have a sponge filter, just pour it slowly in the water and it will settle down on your gravel.
I used 1/4 teaspoon in my 5.5 gallon tank. So since you have one betta too, you could add 1/4 teaspoon, since your bio-load will not be too big. Or, for your 7 gallon tank, you could add 1/4 + 1/8 teaspoon. The directions say you can't overdo it, so add slightly more than 1/4 teaspoon if you want. I poured the Bio-Spira right in using the 1/4 teaspoon.
After the tank is cycled, in 24 hours, you shouldn't need to add any more Bio-Spira. The bacteria will reproduce themselves too. I just added maybe 1/8 of a teaspoon the other day. I had a divider in my tank since I used to have 2 bettas. I only have one now, so I removed the divider. I added the small amount of Bio-Spira to compensate for what I was removing with the divider, but it may not have been necessary. The bacteria will reproduce and live in the sponge filter, gravel, and decorations. So, unless you use an antibiotic medicine that disrupts your good bacteria, you shouldn't need to add any more Bio-Spira. I did just in case, since I removed the divider, but I probably didn't need to. Hope this helps!
P.S. I'm not familiar with Aqua Safe. I did a google search and it said Tetra Aqua Safe is for outdoor ponds only. Is that what you have?
http://www.petsmart.com/products/product_13069.shtml
You could try something like NovAqua. You don't need to remove chlorine, but it provides some slime coat enhancement. The dosage is 10 drops per gallon, but you could use half of that if you're just using it for a slime coat.
Also, don't use an ammonia remover like Amquel or Ammo-lock with Bio-Spira. These products will bind the ammonia and it won't be available to the Bio-Spira. If you use Amquel or a similar product, the Bio-Spira may not work as claimed on the package, since the ammonia remover products will bind the ammonia first and make it unavailable to the Bio-Spira bacteria.