If you get a paper ticket, yes then the ticket stock would be your Gold Card. But as long as they issue you a season ticket on Gold Card stock, or give you a Gold Record Card, it doesn't really matter which you get.
The Gold Card can be used to discount single/return/Travelcard tickets from 09:30 onwards, including during the evening peak. For some journeys, Off-Peak tickets are not valid during the evening peak - but you will still get the Gold Card discount on an Anytime ticket where this applies.
On Oyster, the Gold Card discount will only give you a discount on Off-Peak fares and daily caps. For most journeys (there are exceptions), Off-Peak fares are charged before 06:30, between 09:30-16:00, and from 19:00. In terms of daily caps, everything you are charged from 09:30 onwards will count towards your daily Off-Peak cap - regardless of whether it's a Peak or Off-Peak fare.
It's difficult to generalise with Oyster - as it all depends on the journey you make. For example, if you travel from somewhere outside Zone 1 (say East Croydon) into Zone 1 (say Victoria), there isn't an evening peak. Therefore you would be charged Off-Peak fares at all times except 06:30-09:30. During the evening peak you would get your full Gold Card discount - you would be charged £3.45.
However, if you did the same journey in the
opposite direction at 5pm (Victoria to East Croydon) the Peak fare would apply, and you wouldn't receive a Gold Card discount at all - you would be charged £7.30.
It's probably easiest to look up what you'll be charged on the brilliant
LT Fares website. It explains it all quite clearly IMO.
The time of touching in is what determines what you'll be charged.
So as long as you touch in by 06:30, you will be charged Off-Peak fares and will therefore receive a Gold Card discount, even if you only touch out at 08:00.
Again, if you touch in at 15:30, this is Off-Peak for all journeys and so even if you only touch out at 17:00, you will be charged Off-Peak fares and will therefore receive a Gold Card discount.