BOM/OPL parts help before PCB fab

A reputable PCB house will solidly deliver their minimum standard track & spacing.

Some will let you try finer at your risk and some will reject your work outright if under spec.

I assume that you are using a temperature controlled iron. If not, do.

If you are not confident in your own soldering abilities and you have plenty of room then fattening up tracks and especially pads associated with through hole parts does no harm. I'd give the through hole headers as much copper as you reasonably can - especially if the board is NOT PTH (plated through hole). With PTH you get substantially more strength. If the board is single sided (probably not, but ...) then you want to take great care with through hole pad soldering and due care with everything else.

SMD part pads should be suited to the part and you have to learn to accommodate them rather than them accommodating you.

PS: Others feel free to contradict or improve anything I've said. I have very substantial soldering experience but there is always good stuff and ideas to learn. ________________________________

Related: This excellent reference -
TI Analog Engineer’s Pocket Reference - 4th edition
as well as a vast amount of other useful material
it provides some useful information on PCB track current/ voltage drop / heat / fusing issues. Especially pages 55-68.

are my assertions above correct?

Everything you have written above that line is correct.

This is a multipart question. At the very top system level, you will find surprisingly heavy use of Word and Visio to produce a series of block diagrams. The different specialisations will then be handed off to different teams using individual tools.

Designing a whole new product out of new parts in one go with no prototypes is a risky endeavour. Generally you'd do it in stages: sort the custom ASIC out before finalising the motherboards.

RAM is highly structured and I think the tools for this may be proprietary things that just emit GDSII. Individual RAM cells can be simulated in SPICE.

The final question depends slightly on what you're making, but last time I did it I sent:

• a PCB stackup: set of Gerber files with list of drill holes and thickness/finish (ENIG, soldermask colour, etc)
• a placement list (autogenerated from the PCB software, used for pick-and-place)
• a Bill of Materials (BOM) which is a spreadsheet of parts by part designator
• a test plan for checking the PCBs (Word document with pictures)
• software binaries to be preloaded into the microcontroller (Microchip BIN format)
• assembly diagrams for how to put the PCB in the case, fit buttons etc.

Injection moulded casework was designed in Solidworks and commissioned seperately. If you need things which can't be reflow soldered that involves extra explaining.