[updraught]

On customs regulation, yes, they are strict but fairly logical. We are an island and we are trying to keep out weird bugs and creatures. (we have enough of those already)
Usually, processed food like chocolates and wine are OK. Heck, you can buy them in every airport. However, things like fruit, some weird sausage etc. will be confiscated due to the threat from bugs. Wood items that are clean and have preferably been kiln dried should be OK if you declare it. If it is from Borneo, for example, with the bark on it and it might have bugs in it, it will not pass. Camping gear and boots with soil on it will not pass either. Johnny Depp should have declared his dogs on his private jet. They would have needed to go thru quarantine which takes time.
Often it is quicker to declare something than nothing on entry. If you do the right thing and declare it you should find customs helpful.

Airport security is another matter. Bottles of wine you will need to check on. Also, you may need to transit through countries that don't allow alcohol. There will also be a duty free limit.

If we want a reminder of somewhere we've been we usually buy a set of drink coasters. Find something bright and cheerful. Maybe in this case a Californian surfing or sporting theme. They are small and easy to carry and are always useful.