Skill Discussions

Off the top of my head:

Drones 5
Drone Interfacing 3
Combat Drone Operation 4
Drone Durability 4
Drone Navigation 4
EWAR Drone Interfacing 3
Scout Drone Operation 5

Electronics 5
Long Range Targeting 3-4
Propulsion Jamming 4 (PvP only)
Signature Analysis 4
Targeting 4

Energy Grid Upgrades 4
Energy Management 5
Energy Systems Operation 5
Engineering 5

Advanced Weapon Upgrades 4 (if WU 5)
Controlled Bursts 4-5
Gunnery 5
All other gun supports 4
Weapon Upgrades 4, but get 5 ASAP

Armor Rigging 3-4
Armor compensation skills 3-4
Energy Weapon Rigging 4
Hull Upgrades 5
Jury Rigging 3
Mechanic 5
Nanite Interfacing 4 (PvP only)
Nanite Operation 4 (PvP only)

Acceleration Control 4
Afterburner 4 (PvE only)
Evasive Maneuvering 4-5
Fuel Conservation 4
High Speed Maneuvering 4 (PvP only)
Navigation 5
Warp Drive Operation 4

That plus BC 4-5 and T2 guns (especially pulses) would make for a very happy Harbinger.

Nope. But you did say ideal. You can fly a respectable BC well before that. But of course higher skills are always better (if they're relevant to your ship/fit of course). As a general rule, you can get away with fairly poor skills in a BC for PvE; the competition is a bit more intense for PvP.

The major frustration with lasers tends to be cap, so I'd make sure to get good engineering skills sooner than later. I'm also quite biased towards having good drone skills, but you can get away with far less with a BC (not so much a BS where your drones are sometimes the only thing that can deal with frigates). But beyond that, just poke around and see what different skills do and decide which are worth prioritizing. For instance, if you're not planning on using energy turret rigs, don't bother with the skill. Most have at least some general application though.

(Also note that the Harbinger can be shield tanked. The list I gave ignores that option entirely, but it's not hard to throw in a few shield skills just because.)

Eh. You do and you don't. Drones 5, for instance, is pretty much mandatory. And once you start allowing things like that, you start to realize that at least the other category-named skills fall into the same category. And, again, with a Harbinger, you really, really want to make sure you have enough cap to accomplish whatever you're trying to accomplish.

Otherwise yeah, skipping L5 is by far the most reasonable way to train. Eventually you'll have to get around to it though.

In general, you can get by with most things at 3, but 4 should be done ASAP. And for tier 1 skills (especially Drones, Engineering, and Electronics), have them at 4 before getting in a BC and take them to 5 as soon as you can. I would say Drones is the only one I would definitely say to take to 5 before undocking in a BC, drones to keep frigs off of you just helps so much.

I think what I did when I was getting in a BC (the second time, after I almost lost my first one in a lvl 2 mission because I didn't really have the skills to fly even a cruiser properly) is take everything atleast as high as it can be trained before you start hitting <24h times to increase the level. It's a very rough metric, but it seemed to work ok.

Definitely train towards maxing out Zhilia's list though, that looks like a fairly solid lineup of skills for a Harby.