standallone

I am palnning to buy an external solution with 1 TB size. Please recommend me whether I should buy an standallone external HDD or buy a HDD and use an enclosure?

1]what is the extention on binary files in linux? 2]why cant linux have installers(binaries,like in win)to install soft? 3]if a shared lib in linux in same as dll in win then y each appl requires its own lib?(what i mean here is standallone apps i.e copy paste apps) 4]y not make lib like...