As far as spacing for grid work, think in 3' foot increments. A bounce would be two low jumps 9' apart. A one stride would be 18' apart for trotting in. If you plan to canter it, 21' would probably work better. Best to first find your horse's natural canter stride and space accordingly. Place 2 ground poles 4 to 5 strides apart. (48' to 60') Canter over pole 1, count how many strides it takes to get over pole 2. Do it enough times that you the same stride every time, adjusting the second pole if necessary so your horse can put in full strides instead of have to shorten or lengthen. Once you have that distance, walk it on foot and figure out how many of your strides equal your horses. Then set up your poles.
As for the pulling thing, usually that is a result of locked or unforgiving elbows. Place your hands a few inches further up the neck. Then be sure to follow the motion with your elbows so it is fluid. The jump cue and steering should come from your seat and legs, so the reins should remain as quiet as possible.
It's hard to tell from the pics, but are you coming out of the saddle at all over the jump? It almost looks like you're still sitting.
You just have to see your distance...you don't have to like it.