Time? As in time of day? You want the blinds to open at 7am every day summer and winter?
OK, before we get to details like daylight-saving time, you are going to need a real-time clock (RTC) to add to the Arduino. There's lots of them available. Here's one you might like: http://www.jaycar.com.au/productView.asp?ID=XC4272
Download the library and the examples and start looking at how their code works.
As for working with microswitches, you are on the right track. Google for "Arduino limit switch" to get some ideas.
What pins to use? Well, if you have any shields, the pins they use will be fixed (not easily changeable) so those pins are reserved for those functions. The other stuff you add can go on any pin with the following limitations:
- You probably need to use the serial pins (0 and 1) for serial communication in almost every single Arduino project. Never plan to connect anything else to them. It can also make it impossible to program the Arduino if something else is controlling the serial pins. (Unplug it from the shield to load the program.)
- Analog inputs (sensors reporting 0-5 volts) need to go on Analog pins.
- PWM (simulated analog outputs) is only available on certain pins marked with a ~
- Some devices use I2C or SPI communications with the Arduino. It's best to use the 'hardware' I2C and SPI pins but not a disaster if some other shield is using those pins. These communications can have many devices on the same data bus, addressed independently.
- SPI devices each require one extra 'chip select' pin. Start with the default pin (10) and then use any other pin you like for the subsequent SPI devices.
- When you get to pin-change interrupts (a very advanced topic) then only certain pins can be used.