Welcome! The classic response is to buy from a dealer that will setup the uke for you...Mim or Uke Republic. I do think that's a good idea to get the instrument setup.
Welcome to the forum. You’d best be served to ask your string question in a separate thread that includes the make and model of the uke you plan to use them on. That said, it will ultimately be a personal preference.
Welcome to UU! The best way to figure out the best strings for your uke is to buy different types and try them all. Seriously. It is going to be a personal thing and it will vary depending on the uke, too. Strings you love on one uke, you might not like on a different uke.
Welcome Bnixon from the LBC.
As Peace Train mentioned, it depends.....Make, model, material, and mostly personal preference.
That said, Martin 600 are a good bet as are Aquilla Nyguts.
The good news if that strings are relatively cheap if you don't like one or the other.