When you are conversing with him face to face, say that something you did was rather naughty. Check his reactions. A smirk, or a comment in which he refers to you as 'young lady', would pretty much mean he is into ttwd.
Then, take him shopping! Tell him you need to buy a new hairbrush. A spanko male probably would be keen to join you in the store and help you pick out a good one. Perhaps even testing the back of it against his palm hehe. Most vanillas however, would not be keen to look at hairbrushes and would most likely suggest that he visits the hifi store whilst you seek out the perfect brush! Kitchen stores are a good place for testing whether a man is potentially a spanko. He will glance around at not only any female shopper's bottoms but also the wooden spoons, spatulas, cheeseboards, etc. However, bear in mind that a man who does find hairbrushes and spatulas etc fascinating may well be a switch or even a bottom himself.
What you are doing here is really reading his body language, so no single gesture can be interpreted in isolation of the others. Reading his body language signals in response to your hints is in no way 100% foolproof but still a good way to build your confidence for stage 2 if he is responding favourably!
Now on to stage 2. The honest discussion. You could ask him to share his sexual fantasies whilst in a relaxed moment (over a romantic meal perhaps, or even during a physically intimate moment if you are up to that stage in your relationship). Men are generally quite happy to tell their partners what they enjoy sexually! And it provides a great opening for you to tell him what YOU want too!
Eileena Cross wrote an article in the Wellred Weekly Vol 1 Number 1 entitled: Getting Your Vanilla Partner to Whack Your Butt. Some of the advice in there may be helpful in your situation.

As for whether or not he is a psycho....
Anyone with bad personality traits of any kind should be avoided... ie is he easily angered, do his moods change frequently, is he possessive, controlling, does he constantly want to know where you are and who you are with? These of course are some of the obvious signs to watch out for. But human nature is far more complicated than that so you can never be sure that the sweet, kind guy isn't really a wolf in sheep's clothing until you have gotten to know him very well. For this reason ALWAYS meet in public places using your OWN transport, in the early stages of the relationship. After a few public place meetings you could suggest bringing a supportive friend or family member with you who can give you their honest and trusted opinions.