Does order of structure matter?

[stephensmat]

I'm just getting started with more complex construction now. I'm looking at tutorials, and I'm not sure if the 'order' of parts matters.

If I put RCS thrusters in places other than a fuel tank, does it matter? If I put a fuel tank between a Lab and a segment with several solar panels, does it matter to the flow of electricity? Can I put the batteries anywhere without it affecting anything? Can I put docking clamps or crew-capable modules at any end? Am I overthinking this, or dramatically underthinking it?

[jimmymcgoochie]

Electricity flows through everything in KSP so batteries and solar panels (and RTGs when you unlock those) can be attached anywhere you like. Monopropellant for RCS thrusters does the same, no need to attach those directly to their fuel tanks, but RCS thrusters will drain from across the entire craft ignoring crossfeed rules (e.g. across decouplers) so just keep an eye on it so you don’t run out on a later stage. Fuel cells, on the other hand, need to be attached to a fuel source to work and will obey crossfeed rules when draining fuel and oxidiser, however the power they produce can flow anywhere; the ‘Puff’ monopropellant engine behaves like other (bipropellant) engines and will obey crossfeed rules, but it’s not a commonly used part and you can probably ignore it entirely.

KSP also doesn’t model any kind of internal structure, so docking ports and crew parts don’t need to be attached to each other. As long as they’re on the same vessel (and docking multiple crafts together makes them ‘the same vessel’ until they undock again), a Kerbal can transfer between any crew parts on that vessel with no problems- even if they’re attached via a grabbing Klaw rather than a docking port, through some metal girders, an engine and some fuel tanks.

TL;DR: Power generation and storage, docking ports and crew parts and RCS thrusters can go anywhere on a craft. Fuel cells need to be attached to a fuel tank, but their power flows to the whole craft.