Adjusting the tie rods is probably the way to straighten the steering wheel. However, if you have it aligned, straigntening the steering wheel should be included in that. It's a good idea to have the alignment done anyway, so getting those two things done in the same job is a good thing.
As far as struts, if one has failed, is leaking, etc, then you have to replace them in pairs, front or rear. The fronts are most likely to fail first. I'd give all four corners of the car the "bounce test" and if the rears pass the test, then leave them on till they go bad.
Here's a good little article on checking your struts (shocks).
http://www.imperialclub.com/Repair/Springs/test.htm