I took my girl to the place to meet the boy I adopted. They were first introduced both leashed in case anything happened. And then we had some off leash time with just the two of them in a fenced, secure area. Leashes stayed on even while they were in the fenced area so that if something happened, you can pull the leash and hopefully not get in the middle of a fight.
For us, food was the biggest issue once both dogs were in the house. That's the only thing they've ever fought over. It's up to you how to handle that one. You'll get a wide range of advice on this board. I think most people think it's best to feed once or twice a day in spearate bowls. For us, it worked out well to free feed in one bowl. That's just us. You have to find what works for you all.
Good luck!!