For free roaming, I would not personally let them out of their cage for at least the first two weeks. Especially if they are your first rats. It's a new environment for them and they can get freaked out and potentially injure themselves or get lost in a panic. Slowly start bonding with them first. Every rat is different. Some are just really trusting and friendly from day one. Others need a couple weeks or more.
For bonding. Sit by the cage. Offer them treats. See if they start coming up to you. That's a great sign if they do. By then you can open the cage and stick your hand inside to let them sniff and interact with. If they do that and tolerate you petting them, then you can try picking them up. Some rats never really like being picked up but most do. When you understand your ratty's limits and how to handle them, that's when you can start doing free roam a lot safer.
For rat proofing your room, that's something I can't see but you're right about picking up cords and stuff. Cord protectors won't work great. They can even chew through thin metal. I would say the major one is making sure the door doesn't have a gap they can get under. Rats fit in tight places. Check for holes. They can climb walls and furniture. They jump pretty high and very far. Don't underestimate them lol.
The other major thing is just keeping an eye on the little demons. Anything they can chew they WILL chew. If they love you, they will pee all over you and your things.
You can do free roam in a lot of places. I personally do my bed mostly. Especially their first time. They don't usually like jumping off and it helps keep them contained. Super easy unless you have a desk next to your bed. A place to hide on the bed is great for them but if they trust you before coming out for free roam, they will often hide under you and bond more.
I also do a room for them occasionally. Just make sure there is nowhere they can get lost. I put down a large soft blanket. They don't have to be fleece but make sure it does not have stuffing. Do no use strong laundry detergents on their blankets and hammocks. Unscented or baking soda is best. Rats have very sensitive lungs. You can hit up Goodwill or other thrift stores to find blankets much cheaper and even use the blankets to make hammocks with pear clips (no need to sew). This will save you a lot of money throughout a rat's life.
You can use cardboard to block off areas you don't want them to go. You can secure it with tape or heavy items. Make sure the tape doesn't rip the paint off whatever it's on. You can also use some of those rat play pen panels. Might be easier if you have the money for them but they kind of add up on price.
For toys, rats like all kinds of stuff. All of them have different personalities. Some really really go crazy for those feather toys that cats like. They love cardboard tubes and cardboard houses. Some like laser lights. Paper towels are an absolute treasure to them. There are food toys that make them think to get a reward. Hell food can be a toy in general. Give them a boiled egg and watch the show lol. Some like pea fishing. They really love paper cups for some reason too. Chew sticks. A box of 1" pom poms or shredded paper.
A nice big wheel inside their cage may be their favorite toy. It's hit or miss. I've had some that it was their passion in life. Others never use it. You can see if they even like one by buying one of those cheaper large 12" plastic ones from PetSmart. It's $30 something. The real 15" ones are usually around $140 but totally worth it. 12" is too small for adult rats. Great for younger ones though.
Fresh vegetables are a better daily treat than fruits because of the sugar in fruits. I would not recommend prepackaged rat treats. Lots of preservatives and junk in them. Why give strawberry bites with 30 ingredients when you can just give the rat a strawberry for example. Rats are tumor factories, so the healthier the food, the better. A fat rat will have way more health problems.
Bonus tips. Clean the cage more often the first month. They are probably going to be a little shy. Being shy means they are hiding and they are probably going to pee/poop where they hide. This causes lung problems very quickly. Twice a week at least. Every 3 days is better. You can skip replacing any aspen or paper bedding that isn't soiled. This mostly just applies to hides, blankets and trays
They sneeze their first couple weeks at new houses. That's normal don't panic.
It's your first pair of rats so let me warn you now. They do fall sometimes. It's scary but it happens. Off your shoulder. From the cage. Doing something stupid. They are thankfully really good at surviving falls. My rat Cherry fell like 5 times in her life and lived to almost 3. So don't hate yourself too much if it happens and don't worry too much either.
If you need it, mix antibiotics with baby food. Find a flavor they can't get enough of. Don't force it unless you absolutely need too. Forcing it can make them bite their tongues and a rat tongue bleeds like an ocean.
Rats have a little hiccup thing they do when they are excited or happy. They aren't likely dying if you see them pulsing like that.
Female rats can have citrus, in fact it may help prevent tumors. Male rats on the other hand cannot have citrus.
Never give unripe bananas.
If you have any other questions, never hesitate to reach out to a rat detector.