Ask 10 people and you'll get 12 different answers... However...
Tip number 1 is to run off a report for a fact with sources and ask yourself whether you could find the source again. And a harder test might be - could you go to the Archives containing the paper copy and find the original paper version? After consulting their catalogue, of course.
2) At some point soon you should try and read the Knowledge Base on sources and citations -
https://fhug.org.uk/kb/kb-article/sourc ... new-users/ But take your time over it...
In particular, see the link to "Ancestral Sources" in the bottom section titled "An Alternative Way..." Ancestral Sources is an add-on to FH that should make it easier to produce detailed and consistent sources.
As for your specific questions:
3) Date: Different people do it differently but my belief is that it's best used for when the source was created - which will often be the date of the event
but not always. For instance, on a source for a birth certificate, I usually enter the date of registration there, rather than the date of birth. Doesn't make much difference in the UK but some places have Delayed Registration documents where the registration can be years after the event.
Entering the date that you acquired the source? Some people do that but I've never been motivated to keep that info.
4) Short Title vs. Title. I now enter both - the Short Title I use as (no surprise) a short title for the source record - an easily understood short-hand. The (long) Title I use more as a full description that forms the basis of the report to tell me where something came from. For instance:
Short Title -
Baptismal record: Pitkeathly, Robert, 1788, Perth
(Long) Title -
baptism entry for Robert Pitkeathly, born 13 November 1788, baptised 16 November 1788, parish register volume 9 1787-89, p.196 of 345, hand-written page no. 184
(It's not always possible to find what volume the parish register is, and it's usually not necessary given the other stuff. Page numbers, on the other hand, are useful when stuff is entered out of order).
5) Publication Data - For me, this is the basis of where I found the source. For instance,
Publication Info - digital image in Church of Scotland (Old Parish Registers) Marriages, ScotlandsPeople, citing GROS Data 389/ 50 136
What that means is that what you have in the Custom Id, I'd put in the Publication Data and (Long) Title. Doesn't mean my way is better - it's just different. (I never use the Custom Id).
6) Repository - I would want to make sure that somewhere in my source record, it makes clear whether I got the stuff from ScotlandsPeople or from a visit to the physical archives. One way of doing that would be to set Repository to ScotlandsPeople or NRS (Edinburgh) respectively.
