4. I do have issues with one heel lifting (this is better since getting gel sleeves) and every once in a while, when I lift my foot, I can feel it lifting in the boot.
You can't possibly have a snug fit everywhere, or it would prevent such motion. In particular, you must have a little empty space, or an area of reduced pressure, along the sides of the heel, and maybe a little bit behind the heel, to make room for such motion.
I assume you understand, by the way, that a skate boot should actually snugly squeeze your foot everywhere below the ankle except maybe at the toes, right? Skates don't fit as loose as normal shoes, because almost any motion inside the skate (except the motion ahead of and behind the ankle bones, needed to allow your ankle to point and flex) could easily lead to loss of control and injury. On the other hand, small amounts of motion inside normal a normal shoe (with the exception of certain types of dance and climbing shoe) doesn't do much harm. In effect, due to lever arm issues, skates are like stilts - tiny amounts of uncontrolled motion get telegraphed into huge losses of control of what the blades do.
If I were you, I would be tempted to put something alongside the heels. E.g., add cloth athletic tape under the insole
across the heel, and extending past the edge of the insoles, in such a way that it wraps around the heel. It can stick to the bottom of the boot, under the insole, and sticking as well as it can to the insides of the boot. It may be hard to make it stick for long periods of time - carefully cut moleskin sticks a little better to the sides of the boot, but is a little harder to work with.
And maybe a little something extending behind the heel, sticking to the back of the heel of the boot.
There are other ways to reshape your insole. To form my insoles, I take a piece of foam (I use 6' or 7' long camping pad, bought for $7 at Walmart, because it's cheap, and is skin-safe), and cut it to the exact desired 3D shape with a scissors. I gradually cut it down, and try it again with my foot inside the boot, until it feels perfect. But I used tape first, on the insole, or on a cardboard cut-out traced from the insole, to figure out what shape I want. Regrettably, camping pad foam squishes down over a period of months, so I need to redo it once in a while, but one camping pad provides enough material for many years. I should do it right, with a good quality urethane foam, with a thin layer of moleskin to make it skin-safe. That would retain its shape much longer, I think.
If you saw someone like a good sports podiatrist to get your wedges shaped to you, he/she might be able to help. That's their profession, and they are supposed to understand how shoes work a lot better than those of us who use trial and error to make even the basics work. The only problem is, despite that, some of them don't understand just how snug skates need to be, and don't understand the way forces in a skate work. E.g., a wedge inside the boot or on the boot bottom between the sole and the blade mount, doesn't just create a desired pressure on your foot - instead, to some extent, it just causes the the boot and blade to tilt, sometimes in a undesirable manner - because you are balanced on an edge, not balanced across a large area. (That's not completely true, because the sides of the boot may also create a counter-acting torque that undoes some of the torque effect on the boot and blade - but it's partly true.)
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If you aren't doing one foot glides, it isn't likely that the kind of muscle overuse I was thinking of is happening. I am talking about using muscles on ONE side of the leg and foot to compensate for balance, or reshape a foot to fit a boot. If you are on two feet, you don't need to do that. Though if you are stepping from one foot to the other (e.g., marching), you will need to commit, and place your whole weight (center of gravity) over each foot in turn. You more or less do that even when you are walking in bare feet or normal shoes on the ground, but maybe you forget to do it while you are in skates.
You COULD be making ALL the muscles too stiff. That is another kind of muscle overuse, that could eventually make you sore. I've seen some new skaters, who were so afraid of falling, freeze their muscles so much, they can't pick up a leg, or bend their knees. They say they aren't strong enough to take a step or bend a knee, when they are only fighting their own stiffness. To some extent, you might need to learn to relax a bit. Later, you will use selective muscle tension to create and control desired motions, but at first, a lot of people respond to an initial lack of balance by freezing stiff - which doesn't actually maintain balance very well. You may actually create better balance by relaxing, bending your knees deep into each step, and trying to keep your center of gravity over the base of support - which, on two legs, is midway between the two points of contact with the ice. Also, if you practice falling (gently) frequently enough, you will lose your fear of falls, and stop worrying about them, most of the time. If you have trouble with that, wear padding, gloves, and a helmet - i.e., pretend to be a hockey player.
A good way to understand the principles and methods of balance is to stand on the ground on one bare foot, or on one foot with a shoe on it. Notice how you retain your balance. You can do it by bending the knee a little, and making minor little corrections, to keep your weight over that foot. You can also, short term, make motions with your knee or arms, but that gets a bit complicated, because the benefit is temporary - though it can be long enough for you to push yourself back into balance, or take a step. Note, however, that if you freeze yourself completely stiff, you CAN'T stay balanced.
(Of course, you don't want to be completely loose either - or you will simply collapse to the ground. There is a middle ground, where you have control, but aren't too stiff or too loose.)
Anyway, I apologize for too long a response.