The constant complaint of PC networking folks is that Appletalk it really chatty - lots of overhead. But yes its been able to integrate into an MS environment for some time.
MS Office owes a lot to the Mac. Back when Word on the PC was a command driven green screen application, Word for the Mac, and Excel were great Mac tools. IE was actually a Mac only browser that another company developed and MS bought.
The CPU has been the IBM Power PC, which is RISC for some time. One of the reasons the Mac still dominates in graphics is that the Power PC/Risc architecture is very strong in math, better than equivalent Pentiums, though so was the previous Motorola 68XXX chipset before.
The Mac used to be exclusively SCSI and used to have a propritary keyboard/mouse bus(Apple Desktop Bus) but now is IDE, USB, and PCI/AGP to save money.
OSX really started many years before Linux became popular, and really picked up steam when Steve Jobs came back from Next(which was Unix based too). It did take an extremely long time to come to market. It was an attempt to take the existing interface that Mac users have gotten used to since day 1(1984) and graft it on top of a BSD core. The one button mouse is because there was a one button mouse in 1984, when mice on a PC platform was unheard of(though Unix workstations of the era had 3 button mice). Mac users double click and click which does make some more choices available.
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