Ok hopefully I can somewhat help with the points above :
1. The opened gem slots , be it with gem hammers or the ones you get will stay till your reach the evolution path where you can see the message when trying to evolve as " This item is equipped with gems and cannot be evolved at this time
When this happens , you need to unsocket the gems and evolve and the evolved weapon will have a random number of slots no matter how many slots you had open . I am not sure about true siren to oathbreaker as I did not go through that path,, generally if they are asking you to unsocket gems while evolving that means a slot reset is there, and no matter how many slots you have opened , the resulted evolved weapon have a random number of slots
2. There are multiple ways to get the HM techniques as of now. The Royal Zen bean one unlocks one of the skills of inferno ( middle tree bottom row if I am not mistaken)
the other HM skills for inferno (first n last trees) gets opened by Inferno HM skill purchasable from market place or you can get it as a rare drop from Blood Shade harbor end boss (needs lots of farming). On the other hand , the same can also be purchased from the achievement vendor in the zaiwei town merchant square for naryu silvers , provided you have 1250 or 1450 (not sure about this number ) achievement points . This skill item is the one when activated gives you a series of small quests at the end of which you will receive the skill
Next up is the blazing palm HM skill : This one can be obtained by consuming a few items ,. The list of items can be obtained from under your achievements screen > character> Skills and look for Blazing Palm. All of the items there except the hongmoon pill can be purchased from the achievement vendor in zaiwei merchant square.
Impact skills :
There are 2 different impact HM skills as of now :
a) The first one, i believe this is the first tree under it and is most useful for pvp as well can be obtained from the achievement vendor for 300 reclaimed secret techniques (you get this as a drop in all the new heroic dungeons in silverfrost)
b) The other impact hongmoon skills, which says you need Fateful Tome to activate can be obtained by combining hongmoon secret technique volume 2 chapter 1 and 2 pieces together. The chapter 1 piece drops from 4 man yeti and the chapter 2 piece drops from 4 man necro. Same is tradeable and can be bought from the market place as well
Dragonchar HM skills :
This one can be obtained by using the chilling elixir( not 100% sure of this name , not in game now so cant check too) . There are 2 parts to it too ,you need to combine Asura Ember (dropped from 4 man Soguns Lament) and the elixir you can buy from Cold storage dungeon merchant for the orbs .
Additional HM skills :
The phantom grip hongmoon skill is not available as of now in NA from my understanding . Frankly I do not pvp much anymore so did not check
There is also an additional HM skill , i am not sure for which skill it is , will check and update : That one is also divided into 2 parts . One part you obtain from 4 man nexus (hongmoon secret technique volume 3 chapter 1) and the 2nd part you can get for naksun token/badges from the vendor in mushins tower
Alternatively , all of the above can be purchased from the Whirlwind Valley vendor or the pvp vendor in almost all the major towns and in mushin tower for certain set amounts of pvp currencies. You can check them out and see if they are more feasible (again not sure of the values as I am not in game atm)
3. Yes professions are worth the time and some professions like merry potters /soul wardens etc gives ample opportunities to make gold in game . The outfits for them are very expensive to craft and you need to be at a certain level in that profession to craft them . Also you need the secret techniques (silverfrost secret technique - Merry Potters , etc) to craft some of the special items .
Hopefully I have addressed most of your queries, feel free to ask anything which is not clear
- Another Force Master :D