Some changes are reversible if you stop HRT, some not. Breast growth is not reversible, and sterility (after around 6 months) is not reversible. Probably also ball shrinkage.
The rest (hair, skin, fat distribution) reverts if you stop HRT.
Hormone delivery methods that don't directly involve the digestion (i.e. pretty much all of them except non-sublingual tablets) put less strain on the liver. I'm mentioning gel here because it's what I use, and it hasn't been mentioned yet. To me, it has all the advantages and none of the potential disadvantages of other delivery methods. Injections are invasive, patches can fall off or cause irritation. But as has been said, find the method that works best at keeping your hormone levels both correct and steady, and causes the least hassle and side effects. It may take a bit of experimentation between you and your doc to find that.