I'll give your questions a try.

1- You can probably run all 4 fans off one header on the LT. I don't know the current draw on those fans but you should be OK.
I'm thinking you can run everything you listed without a Power Adjust. But
you can daisy chain up to 6 Power Adjusts via the Aquabus cables if you
need them.

2-I don't use the MPS sensor, but you will need one
comparable to the regular "high flow" sensor with that pump. Someone
else can tell you which MPS sensor to use. My understanding is the MPS
sensors also have temp probe.

3-Hmm depends on what you want, at least two of the inline temp sensors would be nice.

You don't need the Power Connect to turn the LT on/off, as you will be
connecting a normal 4 pin molex power connector to it which will switch
on the LT when the psu powers up. As I understand it, it can be
configured via the Aquasuite software to shut off the power to the 24
pin cable via an alarm.

Only other cable that I think you will need that is not included is one for the flow meter.

For the system you are building, do not waste money on a Power Adjust2 Ultra. These units are intended for use where an Aquaero is not present, and is not necessary in your application.
If you really want to use the DDC pump, get one of these cables http://shop.aquacomputer.de/product_info…roducts_id=2345 plug it into the channel 4 connector and it will operate the pump.
I suggest you get a three wire fan splitter for the fans and run them in pairs of fans, one pair each radiator, on fan channels 1 & 2 of the aquaero 5.
The reason for the pump on channel 4 and the fans on 1&2 is that fan channels 1&2, and channels 3&4 share a common tempereture sensor that limits the loads, if you presd the loads out the heat generated is spread out and less problems result.
Which mps pressure sensor to pick is a problem. Mostly it depends on what you really want. The pressure sensor can be used to measure res fluid level, and if that is the application, just measure the height of the res above the mps sensor location in milimeters, and select the mps sensor. If the res is 35mm above the sensor, the mps40 is good enough. If you want to measure flow through the loop, the High Flow USB sensor and a four pin cable are my choice because you are running a powerfuil pump in a simple loop, so flow should be high.
Personally, I would look at the Aqualis res with the 600 pump like this one: http://shop.aquacomputer.de/product_info…roducts_id=2930 and the aqualsi res of your chouce. The 600 series pump is more than strong enough for a simple loop and can be powered from the Aquaero 5 LT without any problems. The advantage is that the fill level sensor is included in the pump mounting base.
The Aquaero 5 LT can have 8 temperature sensors. Four blade type sensors are included. Personally, I would want four in line sensors, one on the outlet of each radiator to sontrol the fans for just that radiator, and the outher two on the outlets of the CLU and GPU water blocks for trend analysis. Specifically, record the temperature difference between water outlet temperature and CPU/GPU die temperatures. Wait six monthes and check again. If the temperatures are a lot higher, then it is time to take it apart and clean it.
I bought three Aquaero 5 Pros and did not buy the power connect cables. I got tired of the cold boot and date/time reset of the Aquaero 5 and bought three cables. Now I can use the units in standby mode and see the temperature sensor reading with the computer shut down, and I do not have to reset the clocks any more. Your real time clock add on would take care of that though. Also, if you get the Power connect cable and the relay(relais) plug, you can wire up the Aquaero 5 relay to turn off the computer through the power supply shut down if an alarm condition occurs.
I know other people feel that 1/2" id tube is too small, but by personal experiance the 6mm plug and cool tubing and fittings sold by Aquacomputer are perfectly adequate and much easier to work with. And less expensive.
As for the rest, I would get the Aquaero 5 Pro unit with water block instead of the LT unit. The reason is that the Aquaero 5 unit will probably stay the same while the rest of your computer changes and grows up to the next 5 generations. The Aquaero 5 controllers are expandable to an insane degree, so it can grow with your computer and the Pro unit has a wonderful bling effect because of the changing screens with information on it. Also, the IR remote is pretty cool. The XT unit has problems for a small, but loud, number of users in some computer case/power supply combos. The Pro unit does not, you just need to buy the Aquaremote seperatly.
If you use the tubemeter you will need to get a four wire aquabus cable for it, or leave it plugged into the motherboard via USB cable, or get one of these: http://shop.aquacomputer.de/product_info…roducts_id=1969
No, I do not work for Aquacomputer, I just like their stuff.