MacOS – Use shift to select word until next capital letter

Here's how you can get ⌃ Control+arrow keys to work like you describe. Copy the following property list into ~/Library/KeyBindings/DefaultKeyBinding.dict (you can create the directory if it doesn't already exist):

{
    "^\UF703" = ("moveWordForward:", "moveWordForward:", "moveWordBackward:");
    "^$\UF703" = ("moveWordForwardAndModifySelection:", "moveWordForwardAndModifySelection:", "moveWordBackwardAndModifySelection:");
}

This will set up ⌃ Control+arrow to navigate to the beginning of the next word (by using OS X's normal navigation three times: to the end of the current word, end of the next word, then back to the beginning of the next word). I also included a version that works with ⇧ Shift so you can select text as you go.

Caveat: this will only work in Cocoa apps, but I think the normal ⌥ Option+arrow navigation does too. Also, make sure to relaunch your apps!

I don't know a single shortcut to select the word, but you can do it in two steps, by first moving the cursor to the start of the word, then select the word.

1) Move cursor to left of word:

⌥←

2) Select word to right of cursor:

⇧⌥→

Of course you could do a similar thing with moving to the right of the word with ⌥→ then selecting the word to the left of the cursor with ⇧⌥← if you prefer.