Path of Exile free to play in about six hours.

[MonTy]

So I'm planning on getting Resolute Technique... ASAP.

Most Melee characters bee-line to Resolute Technique. It's quite a big DPS boost, along with the satisfaction knowing every hit will actually land. Great way to tell if you're lagging, too.

I've also switched to Infernal Blow from Glacial Hammer. At this point, Blow is doing more than Hammer. I'm still using Ice Nova for my AoE.... I'd like to replace that, but I don't feel like I have very good options for AoE at this point.

Infernal Blow can have some nice DPS while Glacial has the freeze/chill utility. I personally prefer the damage from Heavy Strike. If you stick with Glacial or Infernal make sure you get Catalyse talent in the Templar tree.

Lightning Strike is mediocre damage, but is a pretty big change in spec if you go for this. Will want Iron Grip and Static Blows.

Freezing Pulse is amazing, but again, different spec. You'll want LMP, spell damage, projectile damage, faster cast speed, etc.

I personally like Ground Slam, most people find it boring. Templar's increase area of effect passives help this skill as well.

I used Molten Shell for progression, but once I started Merciless farming I got too used to not using it that I couldn't go back. It does provide nice armor and dps boost if you need it. Saved my life once or twice for sure.

Should I stick with Ice Nova? Swap to Ground Slam?

I suggest making a decision now. If you go with Ice Nova you'll want +spell damage. If you go for Ground Slam you'll want more +physical/higher physical damage weapon. Going too in between will leave your character too weak for Merciless, IMO. If you have incredible gear you could possibly pull it off, but for limited resources pick one or the other and supplement its strength.

I spent a lot of Orbs to get it to 4s, only to giggle as I got the 4l on the first try, and then 5 orbs to get it to 4 red

Hah, grats! I've spent 50 fusings trying to four link an item. But I've also got five link in a few tries. So I'm sure RNG will get you back ;) In the future you'll want to try four-linking items with five sockets, and to try and five link items with six sockets. Being able to link gear does have level requirements; see below.

item level 1 - max. 2 sockets (except the starting weapons)
item level 15 - max. 3 sockets
item level 28 - max. 4 sockets
item level 35 - max. 5 sockets
item level 50 - max. 6 sockets