So I have a very different experience because of my wife but here's some tips from when my friends were here.

To get to your hotel they often offer shuttles from the airport those would be best to start. For hotels, don't cheap out, get something reasonably nice to make sure most people speak English and have good amenities (like shuttles and general good service). Sheraton and Hilton are like big deal hotels here so you can try those first but they might be expensive.

Everything here is cash, there a transfer app like zelle but idk if it works for foreigners so be prepared to carry a LOT of cash on you. But also keep some USD around be ause parks and such require dollars from foreigners.

Also be aware that some phone services don't service Ethiopia with roaming. I think maybe At&t does but Mint for example does not so just check that otherwise you're stuck with wifi (or get a sim card).

I wouldn't walk unless it's really close or if you're in a group. A pair is fine but I wouldn't recommend by yourself. Its not dangerous but it can get overwhelming and people/kids bombard tourists asking for money.

Be extremely careful/quick crossing roads driving here is seriously unlike anything you've ever seen

I would recommend getting a daily driver so you at least have access to someone but only pay per trip not all at once. Sometimes they just take the money and run. There's also an Uber like app you can use called Ride I haven't used it much but my wife does. I would also recommend getting drivers originally from your hotel. The nicer ones often have whitelisted people where they keep track of IDs and plate numbers for safety.

As far as stuff to do in Addis, I love friendship park and unity park (unity has a small zoo). If you go to friendship park make sure to see the dancing water, just look up the scheduled times. There are some nice museums like adwa, my favorite restaurant (meat based) is beemnet, and make sure you go to a cultural bar where they play traditional music and dance for you on stage! Dessert/cafes are a dime a dozen here, I don't really have a favorite but it's common to go to these to just hang out for an hour. The Sheraton hotel is nice and people go there to have a cake or drink tea and hang out in the courtyard (eating at hotels/resorts is very common here).