Cala d'or is a very child- and tourist -friendly place, as is the whole island, so a good choice with a baby!
I'd avoid the main cala d'or beach (Cala gran) as v v busy, if you have a car try Cala sinau, mondrago or Porto Colom, much nicer and smaller. Es Trenc is a beautiful beach, more of a drive, and go early as poss to avoid queues in as it's a single track across salt plains and the car park gets busy, but def worth it, gorgeous shallow sea esp for children.
The marina part of Cala d'or is nice. Lovely villages around - felanitx is pretty (inland), Porto colom and Porto Petro also nice for eating and walking around.
Cala d'or has a big hill down past the beach so depending on which side you're staying it, take a buggy as it'll be a pain to do with a toddler walking if you've also got beach stuff etc.
The other areas pp recommended are lovely but at least an hours drive from where you'll be. Alcudia is at the top of the island, Cala d'or is SE. And rocky beaches etc so maybe not ideal for toddler, and you'll def need rock shoes!
If you do have a car I'd also go to Soller (an hour away at least), it's lovely, and great for kids, has a cute train along the shoreline and a v child friendly beach.
Yes def take iPad etc for the flight. But if it's in school holidays half the flight will be families with dc so you'll be in good company! It's a very safe and child-friendly place, Cala d'or itself is very touristy now so while that means it's a little bit tacky in places, it's perfect for toddlers! We go a lot to near that area, and there's also a fantastic medical centre in Cala d'or (private insurance) which we've made good use of for one reason or another with varying dc over the years 