Here's the microbulator I use - I purchased mine several years ago and on my 2nd pump now.
Tim points to one on his website.
Here's a link to the microbulator I use with the pro pump, its got info for a pump there as well. You should be able to source one cheaper. I paid $30 for my last one.
Compost Tea Brewer - 5 Gallon Mini Microbulator
You can use your smaller pump no problems just don't aerate too long. With a smaller pump time is your enemy so do a shorter bubble say 12-24 hrs max.
I graduated to the microbulator. It makes things go pretty quick and with that much air we know we got the goodies going.
For amounts of microbes. Too much is just enough. A handful of compost and water is pretty cheap. When we start purchasing products like Re-charge or Mammonth-P which are basically compost teas, the price goes up exponentially in comparison. So a few pennies for compost tea vs the store bought stuff.
To be honest I haven't noticed any difference between compost tea and Re-charge. I think I got some re-charge free so I'm OK using it. lol
Like Vulx - same thing. There are much less expensive alternatives. I think we should be building soil sourced from stuff we can get locally as much as possible and it's possible for sure.