First birthday planning

A friend mentioned my son's first birthday party yesterday and i haven't started planning at all. Just the thought of party planning is stressing me out. Just my immediate family and my husband's immediate family makes 30 people. We have extended family who would want to come too. And we'd like to invite a few close friends too. So it'll likely be around 50 people.

I know it's best to keep these events short and after nap time.

We will likely plan a party in the local neighborhood park.

Any tips and advice? Please and thank you! Especially for food and entertainment! There will be mostly adults and some toddlers, kids, and babies.

Do I make a gift registry? How far in advance do I need to send invitations?