What is the top 5 things Weber’s holdfast needs at this point to improve the defensive posture vs a raid or an attack?
Air superiority, not necassarily Aerospace fighters, but yellowjackets, helocopters, etc. Fast deployment would be nice if you could get heavy lift stuff, which doubles as useful for infrastructure. Fast attack is good to, as most pirates should be able to be handled with big guns on fast aircraft. Heavier raids by states would require some heavier equipment, such as your ASF forces.
Intelligence, need to know when the raid is hitting, so satellites that can observe the pirate points, ones that have eyes on the planet after the raid group drops in, etc. If you know where the enemy is, and what they are doing, you can react better than simply setting up a static, or even dynamic defense.
Militia. Train your locals to not panic, to be able to fight back if needed. Import workers in, train them with anti mech mines, Rockets, etc. Get a few work mechs with enough armor to give your fighting boys some time, mount rockets to flatbed trucks so they can fire and flee through a minefield while the air support tags the now slower moving enemy mechs.
Something for the enemy to attack. Empty fuel tanks, lots of concrete buildings with various assortments of metals to ensure proper returns are given, visable work equipment that are all statues. Build up a fortress with enough fakes that the average pirate company looks at it, looks at their intel report, and then shoots their intel officer. Then when they move to attack, use your satellites/ birds to keep track of em, since they are probabbly going to shift to a more lightning raid style attack in order to 'avoid the local garrison'. If they attack the complex because they have enough equipment to do so? Blow it up, and them with it. If nobody attacks? Use it as a training ground for your eventual garrison forces.
Bolt holes. Get your civvies out of the combat zone, and failing that, get them to where they aren't getting targetted down by big stompy mechs. Keep em alive, keep em safe. Keep copies of your tech safe too so it doesn't all go away when a PPC hits the wrong spot.
I know you only asked for 5...
Last thing: Worker mechs. Worker mechs mounted with Rockets. Lots of em using ICE engines to drastically reduce costs. Swarms of em. Use em in infrastructure, build em on site so you aren't as terribly worried about supply line issues. Cheap, set up your own factories making these things primative, with as few logistical constraints as possible. Rockets are great for this because you dont get your worker mechs into prolonged fights, so don't plan on it. Rockets are cheap, your worker mechs are cheap, and a great investment as you can sell them off world if you build too many, and give you time, the literal most valuable currency you can have. Give yourself time to get an actual fighting force. Invest invest invest into your people.