A switching diode has a faster switching time from off to on.

What's should i use for the button 1 and 2?

A Normally Open Single Pole Momentary Push Button Switch

What are the button 3 plus? and button 4 minus?

Button 3 is the 'Plus Button'
With this button you can start the syncronizing without a Midi-Start signal and you can 'push' the
internal Clock-Counter to correct the syncronisation.
Button 4 is the 'Minus Button'
With this button you can 'pull' the internal Clock-Counter to correct the syncronisation.

and finally what does IC5 74(HC)14 TTL mean ?

A 7414 is a Hex Inverter and the HC is the chatacteristics of this partivulat inverter. The TTL stands for transistor transistor logic.

The part numbers given should be universal and you can order most of them online. You may have a difficult time finding all of these parts at a sinlge store.

Good Luck,

Jesse