installing new shower help

I am installing a new shower and toilet in a basment that plumbing has been roughed in by the builder. When I got down to the pipe (2") for the shopwer that was in the cement floor it comes from the wrong direction to where I want the drain to end up. A few questions.

1. Can I install a trap at a 90 degree angle then I put it in and then go 90 degrees again when I come out of the trap so I am heading back in the same direction and then put in the line to connect to the pipe heading up to floor drain.

2. what do I have to do about a vent. any chance the builder already hooked it to a vent some where under the floor. I really don't think I would be that lucky. I took the end cap of the line and there had been so moisture there and I could here the water running when flushed on the other side of the house.

3. The same question applies for the roughed in toilet pipe. any chance it is alread got a vent??

Thanks for any help. this will be the first of many questions I am sure.

Newplumber

Well, the toilet's trap is in the toilet. Other than that, you really don't want to put that many angles in the floor under the concrete...better to jack up the floor and put things where they need to be by the shortest, straightest path to help prevent blockages. I'm sure there is also a limit on how many turns you can do under there, but I don't know the code. If the builder did things right, there should be vents for all of the rough-ins, otherwise, you'd have to rebreak up the concrete to put them in...you need to look for them. Each fixture should be vented, but they can be combined so you don't need multiple runs through the roof.