would a second colony in a system about 8ly away be too much of a hassle?
Logistically, 8ly isn't a huge distance. So unless you're splitting your storage or having to move materials around because of trade disruption then it shouldn't be too stressful.
Defence is the primary concern, as smaller colonies just can't put enough ships 'in the air' to defend themselves properly. So they need some assitance until they grow.
How do the piracy/expedition mechanics work when you have two colonies up instead of one? And, would it be worth the potential gains?
Pirates will start 'activity' in any system you settle, and will throw raids at it shortly after just because it exists. You'll also get a system-wide reduction in accessibility and stability. Which ranges from mildly annoying, to crippling.
Every system you colonise will end up dealing with these random popup events at some point.
If a raid is successful they'll leave for less than a month and then come back. You'll lose some extra stability for a while. And probably also get disruption from missing trade fleets.
In unsuccessful they'll leave for 2-3 months and then come back.
This will continue so long as that pirate base exists. And each subsequent raid will be stronger than the last, with successful raids having a much more noticeable effect.
Expeditions get sent when you start becoming 'too successful'.
This means producing enough goods or materials to be noticed. This can get triggered for any resource, but generally this won't happen until a colony gets to size 5+.
Unless you do heavy industry early, or slot forges/cores into every concievable hole. Which seems to be a good way to attract attention.
If your colonies are widely separated, you might have issues with defending them until they grow sufficiently to maintain large fleets, and have built fortifications. Basically, the closer together your worlds are, the easier they will be to defend.
I've seen expeditions sent for being too good at farming on a poor (-1) farming world. So while it's usually industry or mining that triggers it, it can be anything.
Honestly, I can't be bothered dealing with all this. So I pick a system to settle which has all resources, and only develop colonies there
And then only have disposable tech-mining outposts anywhere else.
Colonies in the same system will support each other with thier fleets, so they can fend for themselves a little earlier and just more competently in general. And you only ever get 1 pirate event at a time to deal with.
Also, unrelated question, but what sort of fleet composition should I have for this stage in the game? I roam around with a handful of cruisers and two carriers, with supply/fuel ships in tow. Works fairly well for general threats, but isn't very capable against heavy opposition. I'd like to expand it without my fleet guzzling every drop of fuel it finds - 36/day is annoying enough.
Personally, I'd flip that composition around and have the majority of my fleet be carriers with just a few combat ships.
Use one of the front line ships as your flagship, and let the fighters create openings for you to exploit.
There are skills which reduce both supply and fuel use fleetwide, and other skills which increase the amount of both which can be salvaged.
There is also a hullmod which reduces supply and fuel use for an individual ship.
Basically, anything will work with the right preparation. Although capital ships tend to be a little too expensive to be a regular part of your fleet.
And carriers are probably the most effective part of any fleet.
-36 fuel/day is not a huge number. When you get to the stage of fighting multiple large fleets back-to-back, your fleet can possibly be drawing 100+ fuel/day, with your reserves being 6000+.
Don't worry. All this means is that you have plenty of content ahead of you.