New 40k player, questions about starting Mechanicus/Skitarii

[Furnace Keeper]

I've never played 40k besides a few recent demo games. I love all things Mechanicus and would like to start an army with the new releases, but I'm uncertain about a few things and fishing for some basic advice. I understand that there is a separate Cult Mechanicus and Skitarii force, but they can ally and basically be one fighting force? I'd like to eventually do that since I love both model ranges, but would one or the other be a better starting point for a new player? Is there a third Mechanicus army book on the way; I've read some things online but am not sure if they're rumors or conjecture?

I hope the questions made sense, I'm pretty new to all of this. I've read background material for years but never actually tried to make and play an army before.

[Kirsten]

There was a rumour about a full mechanicus codex coming this year but I am not sure about that, it didn't resurface. It is pretty easy to combine the two books. I had a 2,000 point game on Sunday, with roughly 1,000 points from each book. Each book has a unique detachment available to it, and you can take both detachments no problem, you just need to pick one to be the primary detachment. I had the Cult Mechanicus as my primary because they have the Tech Priest Dominus and I wanted him to be my warlord.

As for which to start with, that would depend which faction you prefer more model wise, if either. I would say the Skitarii are more traditional, with infantry squads as your troops choices, so might be a simpler introduction to the game. The Cult Mechanicus has a lot more special rules and more esoteric choices, but you need fewer models to make an army.

[Ruadhan2300]

All imperium factions are considered to be Battle Brothers I believe, so Skitarii and Cult Mechanicum detachments can be regarded as one rather large force with some quite specific minimum force-org requirements :P
Realistically you want at least two skitarii squads and two units of kataphrons anyway. and the tech-priest dominus is awesome just to have on table, let alone the abilities he brings.

I picked up the models as they were released, so I can recommend playing skitarii first. no HQ characters, little heavy firepower, just fast paced adaptable infantry which are highly forgiving to play with.
Frankly I could play skirmishes with just those troops and be happy :P
I started with two squads of ten. one of rangers, one of vanguard. they've been a solid skirmish line so far. Throw in some Infiltrators or Rust-stalkers for dedicated melee (keep them in terrain as best you can) and you'll have at least a few hundred points to start you off.

[Furnace Keeper]

Thank you. I like the look of both armies just about the same so it's really all about where is easier to start. It sounds like Skitarii are the way to go. If I go with a unit of Vanguard and Rangers as my foundation, are there any particular weapon upgrades I should look into?

[Ruadhan2300]

My experience so far I'd that I prefer homogenous units. All the same weapons including squad leaders. But that's just me.

When picking weapons you have three options.
Arc rifle, plasma Caliver or transuranic arquebus.

Each is a different range.
Broadly where possible you always want the special weaponry to match range with your primaries. So for vanguard the best options are the plasma or arc. Which have 18 and 24 inch ranges respectively

The extreme range on the arquebus is wasted on vanguard. And the plasma is too short ranged for rangers. So arc rifles are the only option shared by both in my forces.
Vanguard pair beautifully with plasma. The Arquebus is... probably good in groups. I've not gotten a good look at it in battle yet but One Good Shot is usually a matter of luck.. but then, you can boost your accuracy substantially using Doctrine Imperatives. So that's less of an issue.