I am a fan of the healer companion. Even at 2700 item level, I still pull my little Snowy Fawn out, whether it be to get me "just a little more" health in a difficult area, or to increase lower level characters' survivability as we work through Stronghold Heroics. And he's just so darn cute.
I have done some testing on a few of the healer companions and found that the main stats that affect their ability to heal are: power and regeneration. I suggest stacking your companion with power. Regeneration gear is not very common in NW and there are currently no runestones(used by companions) or enchantments which have regeneration on them, so you can not really "stack" a large amount on your companion. However, there are runestones and enchantments, as well as companion specific equipment, with power so you can stack power MUCH higher than you can stack regeneration. The higher the healer's power, the better it heals.
To this end, healer companions that have 3 offensive runestone slots make better healers because you can put a power runestone into each slot. I find that putting defensive runestones on a healer companion does little to increase its survivability, so you may as well make it "really good at its job" while it is alive.
As far as equipment, I won't say much here because that is for a different post, but I will mention that my preliminary testing on companion equipment showed NO increase in healing (from your companions) when using the Loyal Commander piece over the Loyal Master piece. (tested on Fawn of Shiallia, Snowy Fawn, Apprentice Healer, and Lillend)
I also did not detect any increase in healing from the recovery on the Loyal Commander piece (however, i only tested the recovery with the Spring of Life spell the fawn uses which goes down every 30 secs). I have also read from other player testing that it does not work for companions.
A caution when using healer companions: they tend to have a wide roaming area. This is because they try and stay clear of combat which means they can draw in other mobs in the area that you may not have intended to engage. Also, mobs love to chase after your little healer and it will try and run away, again, leading to the risk of unwanted attention.
Influence is one of the currencies required to grow the stronghold. This is one of the slowest to build for most guilds as it has various limits to how much can be attained at once. As such guilds are always seeking more.
At one time the max was 60. In 2015 mod 6 that all changed and the max level was raised to 70, and the entire world changed. This may help explain for you why there seems to be such a difference between levels 0-59 and 60-70.
You may find that most of the focus in Neverwinter is on the max level. In fact most suggest that until a player reaches level 70 that significant pieces of the game remain untouched. This is fairly decent advice.
There is a significant amount of theme material in the game from 0-59 that lets you enjoy the game and become familiar with its mechanics and loot systems. Nearly all the equipment, currency, usable powers, relative dungeon difficulty, and player priorities change after max level is achieved.
Here are some observations about leveling in the game:
If you ask about in PE zone chat, you will often hear variations on 'Don't worry about gold', and 'Gold isn't important in NW'. This is true to an extent, though devs have tried to make gold a little more useful lately, it remains an under utilized currency.
Gold seems valuable when you first start playing, as it is a means to getting various low level supplies. Profession materials, potions, health kits, and even mounts are all purchased with gold in the early days of playing. Nearly all of these are better purchased using AD after you achieve max level.
You will find in the long run though that those guys in p.e. were actually right. For the most part after achieving level 70 the main thing that Gold is used for is moving enchantments in and out of gear as you change up your loadout. Recent changes to professions and campaigns have added more uses, as you can make vouchers that may be important to levelling a stronghold.
Recent mods have added significant value to Gold for the level 70 player.
Stronghold: For the stronghold coffer vouchers can be made through professions and the campaigns. Most but not all campaign currencies have vouchers available. Important ones are Frozen, Fey, and dark currencies are available through the campaigns, as well as gems and surplus EQ that can be made with professions. These tasks take gold as a consumable, often 5 gold at a time.
Mod-10.5: A new style of fishing was introduced with mod 10.5. Its necessary for getting many of the componants needed to put together the new artifact weapon set. One of the 2 styles of bait available is sold for voninblood (no one does this) and gold (everyone does this). This takes significant quantities of gold if you spend a lot of time doing it. On the order of 50 gold for a good long days worth of nothing but fishing. 99 lugworms are ~10 Gold.