"Too many fans ..."
The most common design for mobo fan ports these days can supply up to 1 amp (at 12 VDC max) to the load from EACH port on the mobo. Now the most common fans used in computers draw about 0.2 to 0.3 amps at full speed, BUT for a very few seconds at start-up can pull 2 to 3 times that. Hence the guideline that you normally can connect two fans to each mobo fan header, but not more. Regarding the total number of fans on all mobo headers together, that's not really a problem - the limit is really just the two max per port. I used the word "normally" because there are a few fans available for heavy-duty cooling scenarios that blow a LOT of air and take much more power to do that, so using them on a "standard" mobo fan header needs careful thought.
SP fan designs generally do not consume significantly more power. Their blades are designed to blow air against a higher resistance to air flow than those of other fans designed for unimpeded air flow. It's just that at higher backpressure ( for example, blowing air through a finned heatsink) the fan will blow less air flow.
Corsair Link software will NOT control all the fans. It will control ONLY those fans plugged into the h100i GTX unit. Control of fans plugged into mobo CHA_FAN headers is done by mobo hardware under control of software in the BIOS. For each fan header there is a "Control Loop" that is actually a feedback control for TEMPERATURE, not fan speed. There is a temperature sensor (your particular mobo has several and you get to specify which of these is used for each header Control Loop) and a temperature target plus a few other parameters stored in the BIOS code. As the machine runs it constantly compares the measured temperature to the target and manipulates the speed of the fan on that header to increase or decrease air cooling and get the measured temperature to match the target. Of course, this means that as the system workload changes and heat generation changes, each Control Loop will manipulate its fan's speed to keep the temp on target.
Interestingly, this system does not need the fan speed to do its job. All it cares about is the temperature, and fan speed is just the tool it can manipulate to achieve its goal. Fan speed is sent to the mobo header for measurement for two reasons. One is just to be able to display it to the user for interest. The other is failure alarming - most mobos will send out an alarm if any of the fans it runs fails to send any speed signal back to it (on Pin #3 of its header).
I'm not sure what the mini commander is that Corsair mentioned to you, but I really think you do NOT need it. What I proposed previously uses the Corsair h100i GTX system to control CPU temperature as it is designed to do. That Control Loop system uses a sensor built into the CPU chip itself by its maker and fed out to the mobo on one pin of the CPU module. The Corsair Link software picks up this information from the mobo and uses it to control its own two fans. For your case ventilation fans, however, ideally you do NOT want that CPU internal temperature involved. Instead you want the sensor guiding these four fans to be one that measures the actual temperature of some critical point on the mobo. Its maker has provided one called [MotherBoard] and also two others on specific areas of the mobo in case you feel they are more appropriate. I suggest you start with [MotherBoard] until you have a good reason to change that. Since all four case fans will be doing the same job fundamentally, I suggested that you set all to use the same temperature sensor and the same automatic control system ("Standard Mode") so they will work together.