As a British Citizen and former military member, I looked into it when we visited, but alas I am a retired U.S. service member (long story), so the discount did not apply to me. It only applies to those who served in HM Forces. From what I read, Defence Discount Service Card holders (and I believe those with MOD90 ID Card) can visit Windsor Castle with up to four friends or family for free. If I understood it correctly, it applies to everything on the Castle grounds. Sorry if I am mistaken, but that's the information I have as I interpreted it.

In my opinion the best way is by train, it is a straight forward journey which you can Google. You buy your tickets at the stations

The afternoon is usually best. When I visited, even on a Saturday, by mid-afternoon there was no queue.

Just direct with the Windsor castle website and I think you book a time slot

No. No photography allowed unfortunately

Entry is from stated time till 30 mins after as queues to exibits mean staggered entry necessary . Even with advanced tickets there is security to get through which takes a bit of time as well. If you leave it later they would have right to refuse admission but dont know if they would or not

probably best to reserve ahead for your desired time slot, but you can also get them at the entrance but we booked ahead to avoid wasting time on the day. enjoy, we loved it ! hope that helps

It wasn't a separate ticket, it was included in the admission. You can choose to go in and see it as part of the admission to Windsor Castle.

If you are going to Windsor town/river then you are right beside the castle anyway and it's definitely worth a look. You get good views of the castle (incl tower) from the 'long walk' (Google Windsor Long Walk and you'll see photographs) which is open parkland. And it is only a few minutes walk from the river and right beside the town centre.