Without video, its going to be tough. But it sounds as if your feet are getting fast and that causes a big pull down of the swing. Work on that footwork.

Try holding your ball lower in your starting position. You could also make your first step smaller, these changes can slow you down and your swing will catch up. As far as getting the ball to the right - you might be to square at the line. Also you can try tilting your feet and square up to your target not the foul line.

Indeed, it seems as if timing could be your major problem. Foot speed and arm speed do have to be coordinated. The ball should be pushed or allowed to swing towards your target, towards your ball path or you will pull it inside. The arm swing needs to be close to your body or you can "chicken-wing" it.

Like the previous posters, it's almost impossible to give decent advice without a video.

A coach would help.  If no coach is available, the pro shop operator is a good place to start.  I know, not in every case, but you want your ball drilled to watch you bowl anyway.

Another recommendation would be to visit Magic Carpet's (Ron C) website:

bowl4fun.com 

Its a great starting point and he is currentlt talking about some of the subjects you are concerned about.

BTW, another couple of things I have difficulty understanding are what boards I place my feet on, and how to keep my hand behind/underneath the ball.  I bet this first question sounds silly: If I wanted to walk straight to the foul line to throw the ball up 10, what foot should be on what board in order to have a good swing and get to that target?  Also, is there a trick upon stance/hand setup position and during the swing to ensure at least most of the time my hand is behind/underneath the ball at release?

I too struggle with consistency and pulling the ball. Here four tips that helped me alot and made me more consistent.

1.) Line the center of your chest with your target by opening your hips when you set up. The shoulders should stay open especially if you struggle with pulling the ball. The only time you want to "square up" is when you want to play the lanes dead straight.

2.) Bend your knees throughout your approach. Start low, end low. Make it easy on big bears like myself to stay low and work my way effortlessly throught the approach. Keeping your knees bent, keeps you from straightening up at the line, losing leverage and pulling the ball.

3.) Keep the first step short. It should pretty much be a heel/toe right in front of your left foot, meaning pick it up push the ball away and put it right back down heel/toe style. This will slow you down and align you timing.

4.) Keep your back and shoulders in a striaght line with your knee. You dont want to get in front of your knee, which a lot of bowlers tend to do, because it cause you to lose leverage, put unnecessary strain on your body, and can cause you "stand up on the ball" keep your leverage as long as possible. Standing up cause you to "top" the ball, making it push downlane forever. I dont care how many rpms you have, if you top it, core will work against itself and you aint getting it back when that happens. That why you pick off 10's on strike balls.

All of these tips are approximate. With no visual of you throwing it, i can only assume that those are your issues and these tips will help. I hope they do and good luck with them. Be sure to practice them because its hard to master.

***Sidenote****  isnt it refreshing to have someone legitimately asking for help and not the consistent regurgitation of post like "ball x vs ball y" and "what will this ball do that comes out 2 months from now"?

When you slow down your approach you are not slowing down your armswing the same amount. If your feet are early you either have to pull the ball or loose it out.

Some of your inconsistency could also be due to a bad fit. An incorrect grip can keep you from having a consistent release.

If you can throw a ball right on a THS and only get the 10 pin would indicate to me that you are not lined up properly or have HUGE inconsistency in your release.

As others have said, without a video we are simply guessing.