1.022 is good! I personally keep mine at 1.025 to match my LFS.
About $7 a pound is on par with most LFS's that sell live rock, so you aren't getting hosed or anything... don't worry about what others pay for their LR, it's probably not the same quality as yours unless they networked with some good people.
You can place the powerheads wherever you want. The fish are used to weird currents in the ocean. I would consider a #2 & a #3. The #2's give flow, but for a 55 gallon I think you would need 3 of them to get the right flow for coral down the road, but you can certainly get away with two #2's for now. I would position one on the side glass, about 1/4 from the top & point is to the surface to break up the surface even more, help break up that film on the top of your water. I would take the other powerhead and place it on the back glass, at the far end of the tank & point that powerhead down and at an angle towards the other end of the tank.
I have a corner tank with a #2 & #3, no matter how I set it up it's like one giant flushing toilet in their, so far the coral are thriving and my fish are unphased by this.
As for your skimmer, it seems there are 3 brands that everyone loves. For a hang on the back skimmer, since it looks like you have no sump and are on a limited budget, there is the Aqua C Remora, the Red Sea HOB & the skimmer I will be going with is the Typhoon or Terminator. While the skimmer is important, it's okay to go without one for now.
Do your weekly 5g water changes and proteins won't be an issue. I've read several articles & even my LFS says the best protein skimmer is water changes, but over time that task becomes tedious & with the volume of some tanks, 25g water changes a week are not in the budget & requires too much time.
When you mix your water, take your #3 powerhead and put it in your bucket. It'll completely mix your water in just a few minutes, you can borrow your tank heater & bring the bucket water up to match the temp in your tank. By mixing your water and letting it run for a couple hours, that initial PH spike most people get when mixing water won't happen, you won't shock your fish or any of the critters & coral living in your tank!
The lighting you have right now will grow very little of anything, I think you could maybe do some mushrooms? On the very low end of lighting, your goal should be to get ATLEAST 60 watts of light over your tank. I roughly have 96 watts over my 36g and I've had no trouble with some coral that I've read online needs very high lighting