Mac Mini with Intel 335 240gb ssd questions

i am new to mac and this is my first desktop mac computer.

i am going to attempt to install a 240gb intel ssd 335 series into the mini,

it is 9.5 thick, will that be a problem? i have heard the minis are hot, but i really dont know more than some people saying they run hot, should i return it and get a thinner drive for that reason is what im asking.

could it be paired with the exisiting hdd to make a fusion?

is it relevant to get extended apple care if i hack my computer up?

thanks
i just got it today, and it is beautiful, i am using the track pad, and that is great too, it has been a good start to the relationship to the mac
nate

thanks to you both,

i was concerned that there was something akin to a water sensor on phones to establish how it had been damaged,

it is a slick machine, i have been a windows boy for about 20 years now, once you go mac you dont go back ?


merry xmas