I'm repeating what PPs have said in some cases but my thoughts with now adult children who had parties / went to parties for more years than I care to remember...
How do you stop 10 little boys trashing your house?
Keep them outside as much as possible; be clear which areas are out of bounds; ask any parents who stay to help with that (no such thing as free Prosecco!)
How do you calm them down?
Outside games which require energy if possible. Then a calming game such as Sleeping Lions. Have some cartoons with popcorn up your sleeves for if you feel they need some down time.
On invitations I said parents welcome to stay (mentioned Prosecco and food) or drop off. How many do you think will stay? Hoping lots stay! It’s only 2 hours.
Can't possibly answer that but i would have stayed for Prosecco and food! If you know any of them particularly well, you could enthusiastically encourage them to stay.
Pass the parcel: is it ok to look to ensure all get a turn and your kid doesn’t get the prize or is it meant to be random?
You have to make it look like it's random but you definitely have to make sure each has a gift. Or instead of a gift / as well as you can add a forfeit - makes the game last longer (sing a song, hop on one leg, make a lion noise etc etc)
Is it ok for your kid to win any games? Eg musical statues or should you pull them out?
Anything where you have a part in who wins, eg pass the parcel or statues, bad form for the birthday child to win. Where it's totally objective - eg speed/skill related then that's fair enough.
What’s the etiquette with gifts, do you put them out of reach so birthday boy doesn’t open them in front of friends?
I always put them aside to open after the party. Boring for the other guests to sit around watching birthday child open gifts. Avoids embarrassment if the parent can't afford much, or if there are repeats. Allows your child to enjoy opening the gifts more. Enables you to track who gave what for thank you notes.
Is ok to make everyone take shoes off (I offer disposable pop socks for anyone worried about bare feet)?
Yes - but could you let people know ahead so children can bring slippers if they want? (Bare feet wouldn't have bothered my children but 'there's always one'.
How do you deal if kids act up? Have you ever sent a kid home for bad behaviour
I've only experienced it once with a girl who didn't want to do whatever we had organ9sed and totally disrupted the party, stamping and screaming because she didn't get her own way. I persevered, took her in the kitchen for a quiet chat and a calm down but she was a nightmare. ;With hindsight should have phoned her parents to come and get her. (On that note, make sure you have contact numbers for each child if their parents aren't staying - last thing you need is to be looking after a child who isn't well or hurts themselves, etc etc
I’ve planned games but also free play (garden if warm) but do I let them charge upstairs too?
No to upstairs. They are still young and with that number I think you need them in one place to be supervised. Maybe decide what toys you think would be suitable for free play and have them ready to bring down if needed. (Don't have them in the room where you are trying to organise games as they could be distracted)