I prefer OTM but ATM is an option if that is all there is.
They are current hour if ATM. If an otm is better you could do a next hour expiration.
You need time for it to move. Depends on the market - you trading how fast it moves. This is where expected range comes in. Where are you in the range how much room is left etc… Not a requirement but very helpful. You can even choose a little further out if you want. Today on my morning and afternoon show (they will posted monday i believe in the style section) I talked about price action analysis. Doing this along with momentum scalps can help you easily pinpoint the binary strike for OTM trades (again not required but super helpful) and give you a clue as well on what time is best. In reality e are often in and out o these trades within a couple bars.
The below chart is from the show this morning and afternoon.
I showed how reading where stops are helps me know where I can realistically expect the market to go (SUPER HELPFUL) on OTM binaries
This is basically just a spike striker chart. Using this you can have targets. Then you need something to give you a buy sell (ie a spike striker a momentum scalp (on diagnostic bars) a profit popper (on diagnostic or 4 minute bars) a boomerang on 4 min chart etc…) Do the analysis on the 5 min chart know your target (that means you konw w your strike. Now just wait on a trade to trigger and entry whether it be any of the systems. Very simple very powerful technique.
Only setting is for “visual aid” you may want to look at the historical. Note for just momentum scalps your not locked into the bar sizes on the bar settings page you can use those but they are optimized mainly for elite entries, BMX and MVP reversals.
Feel free to play with the bar sizer and do some backtesting to find what is best for whatever market you want to trade if you want to play with it. 
