...
For pin and symbol naming scheme look at other similar components and follow the pattern, blend in!
Additionally, checkout this guide https://resources.altium.com/p/guidelines-creating-useful-schematic-symbols.
Footprint Making
For the footprint of common components you can reuse the exact same footprint for multiple components. For things like headers it is easy to just add or subtract positions from other similar header footprints just be sure to check the datasheet to be sure the spacing is correct. If you are making your own footprint be sure to check the datasheet and use some basic geometry to determine the exact spacing. I would highly recommend using the footprint wizard as is outlined in the bootcamp for creating unique components as it makes it very easy to extract the values from the datasheet and drop them straight into Altium.
...