“If I get a Linux computer, what kernel?”
Well, first point, Linux is the kernel. And a computer is OS independent and so you just install a Linux distribution onto the computer, instead of Windows. It isn’t a special computer :)
I think what you meant by your statement was if you were to buy a new computer what Linux distro (or distribution) should you install. I would suggest, if you’re totally new to Linux, that you go with either Ubuntu, Fedora or another distro of your choice. I started with Ubuntu, it’s user friendly and has a nice GUI and good support via the community. I now use Fedora but I have tried Gentoo, openSUSE, and a few others lightly.
However, saying all this, you do not need Linux to learn how to program/code. But to answer any further you really need to read Jesse’s post above which is a brilliant statement to anyone wanting to learn how to program :)