Toyota Repair: Frequency Oil change / alignment - 2004 Sienna, wheel alignments, sienna xle

Question
Mr. Ritter,

I have a 6 month old 2004 Sienna (XLE-Limited).

1)  I'll begin with the age-old question of frequency of oil
changes.  My wife drives approximately 600-700 miles a month
in Washington, D.C., suburbs.  My research online leads me to
believe that every 5000 miles is best. Not too conservative, not
to liberal.  Do you agree? But that puts me at an average of every
6 months.  Is this to infrequent a period to wait?

2)  My local Toyota Dealer (Jim Coleman) is offering lifetime 4-
wheel alignments for $99.95.  Unfortunately, they only allow me
to come in once a year.  This seems like a good idea, but I'm
worried that I might need the alignment more frequently...Any
thoughts?

3)  I've noticed that whenever I attempt to take a complete turn
(in a parking lot, for example) with the steering wheel turned all
the way to the right or the left, I hear a screeching from the
tires.  I've checked that the tires are inflated correctly.  Do I need
to take the minivan in (it is still under warranty), or is this
normal?

4)  I can't decide whether or not to buy the extended 7 year
warranty.  I plan to keep the minivan at least that long, if not
more.  A local dealership (not JIm Coleman - from where I
purchased) has offered the warranty for $100 over their cost. It
seems to me that the majority of the problems (the ones that are
covered, anyway) will occur in the first 3 years.  Do you have any
opinion on this.

I realize this is alot to ask.  There is no rush on any of this. Take
your time, no worries.

Thank you, in advance, for your help with all of this.

Sincerely,
Ajay

Answer
I believe the owners manual recommends oil changes every 5000 miles so I would recommend adhering to that, you can change it more often, it's up to you.
I don't recommend buying the lifetime alignment at all, once the wheels are aligned they do not go out of alignment unless there was contact with a curb or a large hole in the road or you run over something, so unless you are using the van off road or on very rough terrain, I can't recommend the lifetime alignment.
If there is a concern at this time take it into any toyota dealer, the warranty period for alignment problems is 3yr/36,000 miles.
The comprehensive warranty is 3yr/36,000, the powertrain warranty is 5/60,000, some emission control system parts are covered 3/50,000, some, like catalityc converters are covered 8yrs/80,000 miles.
I believe that if a vehicle is properly serviced there is no need for an extended warranty, that's my personal opinion.
Some people feel better if they have the added protection of the extra care warranty in case there is a catastrophic failure after the factory warranty expires(transmission or engine failure)it can happen, not likely, but it can, if they offer a 7yr/100,000 mile plan it may be worth it.