Man, so much has changed since I started in the hobby. There are a lot of really nice reactors out there now. The main features I look for when I selecting a reactor are:
no thumb screws (pet peeve of mine, I hate them)
up flow design (lower maintenace as you don't need to clean the slude associated with down flow designs)
quiet, reliable, easily replaceable pump
As for the other items needed. I have never once had an issue feeding the pump with the custom feed pump design that I used. It is a very good alternative for thise wh just can't afford to purchase a dosing pump. The design can be found here:
http://reefkeeping.com/joomla/index.php/component/zine/article/54
As for co2 regulator, I used a simple one like the Aquatic Life. It is one that comes preset and the only adjustment needed was the needle valve.
Putting the co2 on a ph controller is definitely a good way to control co2. I myself chose to tune the reactor the old fashioned way. With my next reactor, I will consider this method as well but really only employ it as a back up plan.
IMO, I see calcium reactors as a truly simple tool that is complicated in this shroud of mystery. There is no magic as to how they work. There is what is needed to make them work and there are a ton of unnecessary upgrades that can make using one easier and less stressful for those that don't have patience.