Need help with simple code for driving a motor and monitoring a "water sensor?"

Hi guys, I'm very new to Arduino and I'm looking for some help or someone to hopefully spit out a few lines of code for me. I have C and matlab training, but its been about 7 years since I've done any programming. I know what I'm looking to accomplish is very simple, I just don't have the time to read through a bunch of tutorials and spend a few nights trying to figure out exactly how to write the code for this.

Background: My GF's is a teacher of a special Ed class who started an organic garden to raise money for classroom materials, b/c our education systems suck. I've been tasked with creating an automatic watering system to make sure her garden doesn't die from lack of water. As cheap as possible.

The Plan: There will be 2X 55gal drums that will collect rain water from the school's gutters. I'll run a cheap garden hose between the bottom of both drums to keep the water levels even, with a "T" fitting between them going to a 12V RV water pump that draws up to 4 amps. **I need 2 portions of code, one basically wasting a day's worth of time then turning on the water pump for 10mins a day. I was thinking it could just count to what ever number was calculated by the Arduino's clock rate and 85800secs/day, which = 23hrs and 50mins. It would then flip on the pump and count to what ever number was calculated with the Arduino's clock rate and 600secs which =10mins. ** Seems simple enough. I will be using the output from the Arduino to a transistor to a relay to the motor. The entire system will be powered by a 12V deep cycle battery and a trickle charge solar panel. I realize I will probably have to adapt the 12V to whatever this bad boy needs, I'll use a voltage regulator. The second portion of code I'm looking for is to monitor the water level in 1 position near the bottom of the barrels to prevent the motor from turning on when the water source is depleted. Also, I need recommendations on the cheapest Arduino that would accomplish this task. I don't care about expansion possibilities bc this will be the sole purpose of this particular module.

Things I need from you guys:
-Recommendation on which Arduino module would be best/cheapest
-Code for timing and controlling motor
-Code for monitoring whether the water sensor is submerged or not
-What I can use as a water sensor

Once I have a starting program, I will understand it instantly and should be able to fine tune it myself with a few tuts and questions. Starting is the hard part. Any and all info is welcome and VERY appreciated by me and about 20 other people.

THANKS GUYS!!! ...OR GALS!!!

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