C / C++ programming, arduino

General information for the business: arduino prototype
Kind of development: New program from scratch
Description of every module: I need a complete system menu for my project that control humidity, heating, cooling and ventilation builded on arduino nano shield
Description of requirements/functionality: my lcd is 16x2 and have keyboard with 6 keys but I want to use just 4 of that..the code that I uploaded is just a sketch to show you the pins setting. Basically I need to set up temperature by 0,1 C° and humidity by 0,1 % when I press up/down keys and this setting manage humidifier, cooler and heater so when a condition changes compared to the setting than the code de/actuate these devices.

I think about a menu like this:
stand by screen show me 'xx.x C° 21/02/14'
'yy.y % 23:59:59' (clock)
by scroll text on stand by screen every 30 seconds what is working
for example 'cooler on' 'heater on' 'humidifier on' 'fan on' (if nothing work, no scroll text)
when I press any keys I visualize the first choise
that is: temperature xx.xC°
then for modify I press 'select' and lcd show (instead of actual temp) set temperature (blinking) and I can set up new temperature by 'up' and 'down' keys by 0.1C° per pressing, then press 'select' for confirm and set or don't press any keys for 3 seconds and lcd show me current temp.
press 'down' or 'up' to move between choices
by press down
second choice is humidity yy.y%
same as above
third choice is fan on/off/auto, then if I press 'select', 'on' or 'off' or 'auto' blink (depends on the current status) and by up and down I can change status by press 'select' again but if I press 'select' on 'auto', lcd show me the timer '00:00' then if I press 'select' '00:' start to blink and by 'up' and 'down' I can set up (0/24) every how many hours it should turn on the fan. then I press 'select' again and ':00' mins start to blink and (same as above) by 'up' and 'down' I set mins. Then press 'select' again to confirm and back screen to fan status.
Now if I press 'down' or if I don't press any keys for 3 seconds, it goes back to stand by screen
that's all for menu draw
and obviously when a condition changes compared to the setting than the code de/actuate these devices.
Specific technologies required: arduino IDE, C / C++
Extra notes: system is done, I need to develop the code
Attached RTC library + pin setting + menubackend file that I think is helpful for build the menu, and missing (because no more that 3 files uploadable) LiquidCrystal.h, Wire.h, DHT.h

PS: I need a C/C++ programmer not an amateur please.
And if you think there is a better way to make the system menu please feel free to suggest me.