I'm a wicket keeper so I rarely field, I like to think of myself as one of the better fielders when I give a youngster the gloves in a midweek or Sunday game though.
My early career as a football goalkeeper has probably given me an advantage in terms of spacial awareness, knowing where the boundary rope is without being able to see it is not too dissimilar to knowing where my posts are when I'm set just outside the 6 yard box.
The only way to get better at spacial awareness is practice, so get someone to stand in the middle and Tonk a few balls into the air towards you on the rope, get used to knowing your limits and it will quickly be like second nature.
As for catching the ball, fingers up would be my preference in this situation, allows you to watch the ball all the way into the hand whilst keeping your head and eyes still, and also if you do fumble, the ball is falling from more of a height than if you take it low, so you have more of a chance to grab it at the second opportunity.