In reply to SiGregory:
Yes it is different. I have taken quite a few people on their first outdoor climb. Most described it as more scary and more difficult.
For example, indoors you have nicely coloured holds to follow, but outdoors you need to find the holds and there might be many options and you may miss the good ones because they are hidden...
Further, indoors the routes tend to go up in a straight line, but outdoors your route may go a meter to the left/right. Believe it or not, it confused a few of my indoor-climbing friends at first.
Definitely step down a grade or two from what you (safely) climb indoors.
Starting with a save toprope is good advice just to get used to the new situation and all.
For the leading you can practice the belay threading at home. Hang two screwgate carabiners somewhere and pretend they are metal rings that you can not open. Then go through the whole procedure.
If you take your time and practice a lot beforehand you should be fine.
Always double/triple check and speak with your belayer beforehand and agree to very clear commands like "slack", "take", "ready to lower" and so on.
In the end safety is the most important but on the other hand it is not rocket science either and by a combination of watching a few good instructional videos (from the BMC or other mountain guides) and practice at home/in the gym you should be fine.
If you have two ropes and two belayers maybe you manage to set up a toprope and then you lead a route with the toprope as backup, do the whole re-threading (could be a bit messy with the second rope though) and lower off on the lead rope again with the toprope as backup.